25 Practical Uses for a Radius Map (With Worked Examples)
By SimpleMapLab·Published 13 May 2026·24-minute read·Updated 13 May 2026
The radius map is the single most-used proximity primitive in business and everyday life — every appraisal, school search, hurricane prep, drone flight, and franchise approval relies on drawing a circle around a point and reading off what falls inside. Below: 25 specific, named, worked examples of when and how to use one, each with a one-click prefilled link into the SimpleMapLab Map Radius Tool.
Each section follows the same shape: who uses it, the workflow, a worked example on a real US location, and the common pitfall that catches first-time users. Every section ends with a one-click link that opens the Map Radius Tool already centred on the worked example so you can compare your own situation against it.
The biggest single use case for radius maps in the US economy is residential real estate: every appraisal, every school search, every "how far am I from a fire station for insurance" question is a radius problem in disguise. The six below cover the bread-and-butter scenarios.
1. School-district commute radius
Who uses it Home-shoppers prioritising access to specific public school districts.
The workflow:
Drop a pin on the home you are considering buying or renting.
Set the radius to your maximum acceptable one-way commute, expressed in miles (typically 10–30 mi for parents) or as a drive-time using the companion Drive Time Map.
Overlay the boundary of every district you would accept, and verify the home falls inside one of those polygons — the radius is necessary but not sufficient.
Worked example — Austin, TX · 30 mi radius. A 30-mile circle from downtown Austin reaches every district usually short-listed by relocating parents — Eanes ISD, Lake Travis ISD, Round Rock ISD, and Leander ISD — while excluding the long-tail commute zones in Williamson and Hays counties that look close on a map but routinely run 75 minutes during rush hour. Open this radius in the tool →
Common pitfall. "Top-rated" does not mean "best fit." A 60-minute congested commute is more punishing than a 90-minute off-peak one. Combine the radius with a real drive-time check before signing.
Who uses it Buyers, insurers, and rural homesteaders evaluating fire, police, and EMS proximity.
The workflow:
Centre the radius on the property address.
Set radius to 5 miles to mirror the ISO Public Protection Class "responding station" distance rule of thumb.
Confirm at least one staffed fire station, one police station, and one hospital with an emergency department fall inside.
Worked example — Boulder, CO · 5 mi radius. Boulder properties inside a 5-mile radius of City of Boulder Fire-Rescue Station 1 (downtown) generally hold ISO PPC ratings of 2–4. Move that same circle 7 miles west into the foothills and the rating typically jumps to PPC 9 — a homeowner-insurance premium increase of 20–40 % on identical structures. Open this radius in the tool →
Common pitfall. Distance to the station is only one input to ISO grading; water-supply infrastructure and the station’s actual staffing model also drive the rating. Ask the carrier for the property’s current PPC before celebrating.
Who uses it Appraisers, agents, and investors pulling comparable sales.
The workflow:
Centre on the subject property.
Start with a 0.5-mile radius in dense urban markets, 1 mile in established suburbs, and up to 5 miles in rural markets where active comps are rare.
Pull every closed sale inside that radius from the last 90–180 days, then filter on bed/bath/sqft to converge on the final three to six comps.
Worked example — Park Slope, Brooklyn, NY · 0.5 mi radius. In Park Slope, a 0.5-mile radius from any townhouse routinely surfaces 40–60 closed sales in the last six months — more than enough to meet Fannie Mae’s appraisal requirement of at least three recent comparables within one mile. The same 0.5-mile radius dropped on Polson, MT typically returns zero recent transactions, forcing the appraiser out to 10+ miles and an entirely different methodology (Form 1004C, manufactured-home or rural-property variant). Open this radius in the tool →
Common pitfall. Crossing a school-district line or a flood zone inside the same radius can change "comparable" to "not comparable" overnight; verify the comps share zoning and hazard status, not just distance.
Who uses it Buyers, insurers, environmental consultants screening proximity to industrial sites, fault lines, or floodplains.
The workflow:
Pin the hazard — chemical plant, refinery, fault line trace, or 100-year floodplain centroid.
Use the buffer distance prescribed by the relevant regulator: 1 mile for most EPA Risk Management Program Tier-1 facilities, 0.4 km (¼ mile) for Alquist-Priolo fault zones in California, 1 mile from a Superfund National Priorities List site for typical due-diligence screens.
Read off the populations, schools, and water bodies inside the buffer.
Worked example — Hayward Fault — Oakland, CA · 1 mi radius. A 1-mile circle centred on the Hayward Fault trace through downtown Oakland captures roughly 90,000 residents, 14 K-12 schools, and the BART transbay tube on-ramp — a useful shorthand for "neighbourhoods that will need to act fastest" when the next M7 rupture occurs (the USGS puts that probability above 70 % within 30 years). Open this radius in the tool →
Common pitfall. Regulatory buffer distances vary by chemical, jurisdiction, and decade. Always cite the specific rule (EPA RMP, Alquist-Priolo, OSHA PSM 1910.119) you are applying instead of "a 1-mile radius is the standard."
Who uses it Car-free residents, urbanists, retirees, parents of teens, anyone testing the "15-minute city" thesis on a real address.
The workflow:
Centre the radius on the candidate apartment or house.
Set radius to 0.5 mile (≈ 10-min walk at 3 mph) for daily-errand walkability, 1 mile (≈ 20-min walk) for "I rarely need a car," or 1.5 miles for transit-adjacent suburban walkability.
Verify a grocery store, a transit stop, a primary-care option, and a third place (coffee shop, library, park) all fall inside.
Worked example — Pearl District, Portland, OR · 1 mi radius. A 1-mile circle from the Pearl District core in Portland encloses 16 supermarkets and grocers, 4 MAX light-rail stations, 9 parks larger than a city block, and roughly 35,000 residents — the canonical "you can live here without a car" footprint for an American mid-tier city. Open this radius in the tool →
Common pitfall. Pedestrian walkability is not the same as cycling- or transit-isochrone walkability; a 1-mile haversine radius ignores hills, freeways, river crossings, and unsignalled arterials. Always sanity-check on foot.
Who uses it Airbnb investors and STR operators sizing demand around a tourist anchor.
The workflow:
Pin the tourist anchor — National Park entrance, ski resort base, ballpark, beach access point.
Set radius to 10 miles (typical "drove past it from town" range) or 30 miles (typical "willing to stay nearby" range).
Cross-reference the population, hotel inventory, and short-term-rental count inside the radius to estimate competition versus demand.
Worked example — Sevierville, TN (Smokies gateway) · 10 mi radius. A 10-mile radius from the Sevierville/Pigeon Forge corridor — the principal western gateway to Great Smoky Mountains National Park (12.5 M annual visits) — encloses Gatlinburg, Pittman Center, and roughly 11,000 active short-term rental listings as of late 2024. That density is what makes Sevier County, TN the second most STR-saturated county in the United States after Maui. Open this radius in the tool →
Common pitfall. Local STR regulation is the dominant risk factor — Sevierville is permissive, Asheville and Sedona are restrictive, Honolulu is hostile. Distance to demand only matters if you are legally allowed to operate.
Service businesses publish a service area, restaurants publish a delivery zone, and franchisors enforce exclusive territories — all of those are radii drawn around a building. These five are the operational backbone of the small-business use of radius maps.
7. Service-area definition for trades and field services
Who uses it HVAC, plumbing, electrical, mobile-grooming, locksmith, on-site IT — anyone publishing a "we serve within X miles" footprint.
The workflow:
Centre the radius on the shop or dispatch hub.
Set radius to the maximum profitable drive — typically 20–30 mi for residential trades, 50–60 mi for commercial-scope work, or by drive-time using the Drive Time Map.
Publish the radius on the website, in the Google Business Profile service-area, and in the dispatch software so jobs outside are auto-declined.
Worked example — Charlotte, NC HVAC dispatch · 30 mi radius. A 30-mile circle from uptown Charlotte covers Concord, Gastonia, Rock Hill, and Monroe — the suburban ring where Charlotte-based HVAC firms typically capture 80 % of their residential service tickets without paying overtime on long return drives. Push the radius to 45 miles and you hit Statesville and Salisbury, where overtime and missed-appointment risk start to dominate gross margin. Open this radius in the tool →
Common pitfall. A circle is not a service area; it is the bounding case. Real service zones are usually convex hulls of profitable past jobs, not perfect circles. Use the radius for marketing, then refine.
8. Delivery-zone planning for restaurants and retailers
Who uses it Independent restaurants, DTC retailers, dispensaries, florists, anyone running their own driver fleet.
The workflow:
Centre the radius on the kitchen or warehouse.
Set radius to the longest acceptable round-trip drive given food-quality decay (5 mi for hot pizza, 10 mi for cold items, 25 mi for furniture).
Tier the zone — free delivery inside 3 mi, $4 fee from 3–6 mi, no service beyond 6 mi — and configure each tier in the POS or delivery-platform settings.
Worked example — Pittsburgh, PA pizzeria · 5 mi radius. A 5-mile radius from a Strip District pizzeria covers all of downtown Pittsburgh, the South Side, Lawrenceville, Squirrel Hill, and the western half of Oakland — the boroughs where a slice arrives in the customer’s hand under the 15-minute "hot quality" threshold most operators target. Outside the 5-mile ring, the slice cools enough that satisfaction scores fall by roughly a half-star, even when the route is technically faster off-peak. Open this radius in the tool →
Common pitfall. Bridges, rivers, and one-way streets break the haversine assumption hard — a 5-mile circle in Pittsburgh is not the same operational footprint as a 5-mile circle in Indianapolis. Always pair with drive-time isochrones.
9. Franchise territory and non-compete enforcement
Who uses it Franchisors, franchisees, attorneys drafting or auditing exclusive-territory clauses.
The workflow:
Centre the radius on the existing franchise location.
Set radius to the contractual exclusivity distance — common values are 1.5 mi for QSR (Subway, Dunkin’), 3 mi for casual dining, 5–10 mi for fitness and personal-care chains.
Confirm the proposed new site falls outside every existing radius before the franchise development committee approves.
Worked example — Indianapolis, IN QSR territory · 1.5 mi radius. A 1.5-mile radius around each existing Subway in downtown Indianapolis (the historical exclusivity radius from Subway’s franchise disclosure documents through the 2010s) effectively forbids opening a new store anywhere inside the Mile Square plus most of Fountain Square — a constraint that pushed new development to Speedway and Broad Ripple instead. Open this radius in the tool →
Common pitfall. Exclusivity clauses vary by year, by franchisor, and by signed amendment — always read the actual contract before relying on a default radius. Most modern QSR contracts have shrunk or eliminated exclusive radii entirely.
Who uses it Site-selection analysts, retail strategists, commercial brokers evaluating a candidate location.
The workflow:
Centre on the candidate site.
Set primary trade-area radius — Costco models a 15-mile primary catchment in suburban markets, Walmart 10 mi, Whole Foods 3 mi, neighbourhood drug stores 1 mi.
Compute population, household income, and competitor count inside the radius before signing the lease.
Worked example — Naples, FL Costco screen · 15 mi radius. A 15-mile primary catchment around the proposed Naples, FL Costco encloses roughly 320,000 residents with a median household income of $82,000 — the kind of demographic profile that justifies a warehouse-club format. Drop the same radius on Springfield, IL and the same 15-mile circle returns 215,000 residents at a $58,000 median, the borderline below which Costco rarely opens. Open this radius in the tool →
Common pitfall. Trade areas have inner cores, primary rings, and secondary rings — the single-radius approximation is only the start. Stratify by drive-time once the radius screen passes.
Who uses it New business owners verifying that a candidate location is far enough from the nearest competitor.
The workflow:
Centre on the candidate location.
Set radius to the operationally meaningful competitor-exclusion distance for the category — 0.5 mi for specialty coffee, 1 mi for boutique gyms, 3 mi for full-service supermarkets.
List every competitor inside and decide whether the local demand can support both, or whether to move.
Worked example — Asheville, NC coffee opening · 0.5 mi radius. A 0.5-mile radius around a candidate cafe location on Lexington Avenue in Asheville already encloses 6 independent specialty coffee shops plus a Starbucks — a saturation level above which most coffee operators move the candidate site rather than try to capture share. Shift the radius two blocks east into the River Arts District and the count drops to 2. Open this radius in the tool →
Common pitfall. Counting competitors inside a radius ignores foot-traffic differences across the same radius — a coffee shop on a 30,000-pedestrian-per-day arterial competes differently than one on a parallel side street, even at identical distances.
Once you have a radius tool open, surprising amounts of life decisions get easier — where to meet a friend halfway, which jobs to filter out of a search, how far is too far from the parents. Five of the most common personal-life radius problems.
12. Meet halfway — finding the midpoint between two places
Who uses it Long-distance couples, friends in different cities, custody-exchange parents.
The workflow:
Use the Distance Between Two Places tool to compute the midpoint.
Centre a radius on that midpoint.
Set radius to 15–30 miles, depending on how flexible "halfway" is, and read off the towns and venues inside that ring.
Worked example — Chicago–Detroit midpoint (≈ Battle Creek, MI) · 25 mi radius. The midpoint of the I-94 corridor between Chicago, IL and Detroit, MI sits roughly at Battle Creek, MI (≈ 42.32° N, −85.18° W). A 25-mile radius around that midpoint encloses Kalamazoo, the Gull Lake area, and a half-dozen state parks — the canonical "halfway weekend" set for couples splitting the drive on a Saturday morning. Open this radius in the tool →
Common pitfall. Great-circle midpoint is not driving midpoint when the two cities are joined by a curved or congested route. Verify driving time on each leg, especially across Chicago metro traffic.
Who uses it Job seekers who would rather walk away from a role than commute beyond their tolerance.
The workflow:
Centre the radius on your home address.
Set radius to the maximum one-way commute you would actually sustain — 15 mi if you have kids in school, 25–30 mi if you are flexible, or convert to drive-time via the Drive Time Map.
Filter LinkedIn, Indeed, or company career pages to only roles where the office sits inside the radius.
Worked example — Atlanta, GA job-search radius · 25 mi radius. A 25-mile circle from Midtown Atlanta captures Sandy Springs, Cumberland/Vinings, the Perimeter office cluster, Dunwoody, Marietta, Decatur, and Hartsfield-Jackson — essentially every major Atlanta employment node except Alpharetta. Push the radius to 35 miles and you add Alpharetta, but with a 75-minute peak-hour commute most candidates regret accepting. Open this radius in the tool →
Common pitfall. Distance is a poor predictor of commute pain in metros with rush-hour congestion. A 15-mile commute through Atlanta’s I-285/GA-400 interchange is harder than a 30-mile commute through suburban Wichita.
Who uses it Adult children planning a move to live near aging parents or grandparents.
The workflow:
Centre the radius on the parent or grandparent’s home.
Set radius to the maximum tolerable response distance — 10 mi for "I can be there in 20 minutes," 20 mi for "same day, no problem," 50 mi for "weekend visits only."
Filter home searches and school enrollments to inside the radius.
Worked example — Tampa, FL 20-mile family radius · 20 mi radius. A 20-mile circle from a parent’s home in downtown Tampa covers St. Petersburg, Clearwater, Town ’N Country, Brandon, and Riverview — a four-county footprint that includes both top-tier school districts and most working-age neighbourhoods. The same circle dropped on Naples, FL is one-third the size by population and forces a 90-minute drive to reach a major hospital. Open this radius in the tool →
Common pitfall. Hospital and pharmacy distance from the parent matters as much as the child’s distance from the parent — a 20-mile family radius around a remote parent home may not include either.
15. Pet-walkable distance to vet, park, and groomer
Who uses it Dog owners, urban cat keepers, anyone whose animal needs a walk-or-Uber-only reach to services.
The workflow:
Centre on the home.
Set radius to your one-way walking tolerance with the animal — 0.5 mi (≈ 10 min) for a senior dog, 1 mi for a young dog, or 0.25 mi for a cat carrier under your arm.
Verify a 24-hour emergency veterinary clinic, a primary vet, and at least one off-leash green space fall inside.
Worked example — Manhattan emergency-vet radius · 0.5 mi radius. A 0.5-mile circle from the Upper West Side at 79th and Broadway covers two 24/7 emergency veterinary hospitals (Animal Medical Center is just outside, but BluePearl and Veterinary Emergency Group sit inside), three primary-care veterinary practices, and the off-leash hours of Central Park — the kind of saturation rural pet owners cannot replicate within a 30-mile drive. Open this radius in the tool →
Common pitfall. Vet hours of operation matter as much as distance. A primary vet 0.3 miles away that closes at 6 pm Friday is no substitute for a 24/7 ER vet at 2 miles.
Who uses it Anyone testing the "15-minute city" thesis on their own address — work, gym, groceries, school, healthcare all within a 15-minute walk or bike.
The workflow:
Centre on the home address.
Set radius to 0.75 mi (≈ 15 min walking) or 2 mi (≈ 15 min cycling).
Verify all of: grocery store, primary-care physician, pharmacy, K-12 school, transit stop, gym, and a third place fall inside.
Worked example — Brookline, MA — 15-minute walk · 0.75 mi radius. A 0.75-mile radius from Coolidge Corner in Brookline, MA encloses three full-service supermarkets (Trader Joe’s, Whole Foods, Stop & Shop), two T stations on the Green Line, the Brookline Booksmith, four pharmacies, Brookline High School, and Brookline Hills public library — the rare US neighbourhood that hits every 15-minute-city checkbox at the 15-minute walking threshold. Open this radius in the tool →
Common pitfall. A 15-minute city around your apartment is not a 15-minute city around your child’s school or your spouse’s job. The thesis applies one address at a time.
Evacuation footprints, hurricane wind fields, and trauma-center reach are radii drawn against the clock. Three high-stakes use cases where the math is identical but the consequences of getting it wrong are not.
17. Evacuation-zone planning
Who uses it Homeowners in wildfire-, hurricane-, and hazmat-prone areas; emergency-management staff drafting plans.
The workflow:
Centre on the hazard source (wildfire ignition point, chemical plant, dam, hurricane forecast position).
Set radius to the prescribed evacuation buffer — typically 1–5 mi for hazmat incidents (per ERG 2024 isolation distances), 10–25 mi for major wildfires depending on wind, or storm-specific for hurricane cones.
List the ZIPs, schools, and care facilities inside, and verify the evacuation route capacity can clear them in time.
Worked example — Paradise, CA wildfire perimeter · 5 mi radius. The 2018 Camp Fire reached a 5-mile radius from its ignition point in Pulga, CA within roughly 90 minutes — inside which sat the town of Paradise (population ≈ 26,000 at the time) with a single primary evacuation route, Skyway. The five-mile radius is the canonical worst-case fire-spread distance under high-wind conditions in chaparral and conifer fuels, and it is the buffer many counties now use for pre-evacuation warnings. Open this radius in the tool →
Common pitfall. Wind direction collapses any symmetric radius into a tear-drop in real fire and plume events. The radius is a planning baseline, not the actual hazard footprint.
Who uses it Coastal residents, supply-chain planners, insurers tracking exposure to a forecast cyclone.
The workflow:
Centre the radius on the forecast storm position (the NHC publishes a 3-, 5-, and 7-day track and a "cone of uncertainty").
Set radius to 100 mi for the typical hurricane-force wind radius extension, or to 300 mi for the tropical-storm-force wind radius for a major hurricane.
Read off the population, ports, hospitals, and refineries inside the radius to size the exposure.
Worked example — Tampa Bay landfall scenario · 100 mi radius. A 100-mile radius drawn around a hypothetical Tampa Bay landfall point captures roughly 6 million residents, the Port of Tampa Bay (the largest port in Florida by tonnage), MacDill Air Force Base, three Level I trauma centres, and the I-4 corridor as far north as Lakeland — the population and infrastructure footprint that determines whether a storm becomes a national news event or a regional one. Open this radius in the tool →
Common pitfall. The NHC cone shows track uncertainty, not wind-field extent. A storm 80 miles east of the cone centreline can still bring 70-mph gusts to your address; size the radius from the wind-field, not the centre point.
Who uses it Rural residents, EMS planners, expectant parents, anyone for whom the "golden hour" matters.
The workflow:
Centre on the home address.
Set radius to the survival-window distance for time-critical conditions — typically 30 mi (≈ 30-min drive) for STEMI cardiac care, 50 mi for Level I trauma reach in suburban markets.
Verify at least one ED, ideally with the appropriate certification, falls inside.
Worked example — Cody, WY trauma reach · 50 mi radius. A 50-mile radius around Cody, WY contains exactly one hospital with an emergency department — Cody Regional Health, a Level IV trauma center — and no Level I or II facility. The nearest Level II is in Billings, MT (≈ 105 mi), and the nearest Level I is in Salt Lake City (≈ 460 mi), a flight that is the difference between life and death in a severe blunt-trauma case. Open this radius in the tool →
Common pitfall. A hospital inside the radius is not the same as a hospital with the appropriate trauma-, stroke-, or cardiac-certification. Check the certification, not just the building.
Drone pilots, ham operators, anglers, and day-hikers each have a discipline-specific radius they live inside. Four niche uses where the legal or physical reality of the radius matters more than the visualisation.
20. Drone flight range under FAA Part 107
Who uses it Part-107 commercial drone pilots planning a flight under visual line-of-sight (VLOS) rules.
The workflow:
Centre on the planned launch point.
Set radius to 0.25–0.5 mi — the realistic VLOS distance at which a human eye can resolve a typical sub-250-g drone against the sky.
Verify the entire radius is clear of FAA Class B/C/D airspace ceilings (or you have obtained a LAANC authorisation), of stadium/special-use TFRs, and of non-participating people.
Worked example — Papago Park, Phoenix, AZ drone flight · 0.5 mi radius. A 0.5-mile VLOS radius from a launch point near Hole-in-the-Rock in Papago Park, Phoenix sits entirely outside Class B airspace (the inner ring around PHX) and clear of Sky Harbor’s Class D — making it one of the few intra-Phoenix locations where a Part-107 pilot can fly without LAANC authorisation as long as the drone stays inside the radius and below 400 ft AGL. Open this radius in the tool →
Common pitfall. VLOS is not a fixed distance — it depends on the drone’s visibility, ambient haze, the pilot’s eyesight, and lighting. 0.5 mi is the practical ceiling for most consumer drones in good conditions, much less in marginal ones. Never trust the FAA waiver of VLOS as a substitute for actually being able to see the aircraft.
Who uses it Licensed ham radio operators planning portable, mobile, or emergency-comms operations.
The workflow:
Centre on the repeater’s antenna site.
Set radius based on the band — 30–50 mi for typical 2 m / 70 cm voice repeaters on a high site, 5–15 mi for HT-to-HT simplex at street level, hundreds of miles for HF.
Layer terrain via a radio-propagation tool (CloudRF, Radio Mobile) for the actual usable footprint — the radius is the optimistic flat-earth bound.
Worked example — Mount Olympus, Salt Lake City, UT 2 m repeater · 30 mi radius. A 30-mile radius from a 2 m repeater on Mount Olympus near Salt Lake City covers the entire Wasatch Front — Ogden in the north, Provo in the south, Tooele in the west — the corridor that holds roughly 80 % of Utah’s population. Move the same repeater to the floor of the Salt Lake Valley and the practical coverage collapses to about 5 miles thanks to terrain shadowing. Open this radius in the tool →
Common pitfall. Radio coverage from a flat-earth radius almost always overstates reality; expect the actual footprint to be a wedge or fingered shape, not a circle. Use the radius for opportunity scoping, then validate with a real propagation model.
Who uses it Hunters and anglers near state lines, river systems, or reciprocity-agreement zones.
The workflow:
Centre on the planned hunting or fishing spot.
Set radius to 5 mi (the typical practical buffer for confusing state-line situations on small parcels) or to the actual state-license reciprocity distance where one applies.
Verify which states’ licenses are valid inside the radius and which require crossing a clear boundary.
Worked example — KY/TN state-line angling · 5 mi radius. A 5-mile radius near the Cumberland River on the Kentucky/Tennessee line illustrates the trickiest US fishing-license situation: Dale Hollow Lake straddles both states, both states honour the other’s license for that specific reservoir (under a long-standing reciprocity agreement), but a tributary on either side reverts to the in-state-only rule. The radius is a useful "did I just cross?" check when wading. Open this radius in the tool →
Common pitfall. Reciprocity rules change by water body and by year — KY/TN, MO/AR, IL/MO, and VA/MD all have body-specific agreements that override the general rule. Check the current regulations before you cast.
Who uses it Day-hikers and weekend backpackers planning trips reachable from home.
The workflow:
Centre on home.
Set radius to your day-trip drive tolerance — 60 mi for "easy morning," 90 mi for "early start," 150 mi for "I will drive farther than I will hike."
List the trailheads inside the radius and pick by season, difficulty, and crowd.
Worked example — Denver, CO 90-mile day-trip radius · 90 mi radius. A 90-mile radius from downtown Denver encloses Rocky Mountain National Park (Bear Lake, Longs Peak access), Mount Blue Sky (formerly Mt Evans), Pikes Peak, the entire Indian Peaks Wilderness, and the Maroon Bells area is just at the edge. That single circle is why Front Range hiking culture is unrivalled in the lower 48 — the day-trip menu inside the radius is denser than anywhere comparable in the US. Open this radius in the tool →
Common pitfall. Highway distance is not driving time in the mountains. A 90-mile straight-line radius in Colorado can be a 2.5-hour drive in summer and a 5-hour drive in a snowstorm; size your day-trip plan to the drive, not the radius.
Where official catchment polygons exist — school zones, voting precincts — a radius is the canonical sanity check. Two civic-analysis use cases that journalists and election officials run constantly.
24. School-district catchment analysis
Who uses it Parents, journalists, district-equity researchers comparing the radius around a school to its official attendance boundary.
The workflow:
Centre on the school.
Set radius to the typical walking distance for the grade band — 0.5 mi for elementary, 1 mi for middle, 1.5 mi for high school. These are the distances at which state law in most US states stops requiring district bus service.
Compare the resulting circle to the school’s actual attendance-zone polygon. Gaps and overlaps reveal where the district has drawn unusual lines.
Worked example — Nashville, TN elementary catchment · 0.5 mi radius. A 0.5-mile circle around an East Nashville elementary will typically include ~1,800 K-5 children based on residential density — but Metro Nashville Public Schools’ actual attendance zone for that same building often pulls from a 4-square-mile area to balance enrolment across magnet and zoned slots. The gap between the radius and the polygon is the school-choice story. Open this radius in the tool →
Common pitfall. Attendance-zone polygons change by school year; always pull the current zone from the district’s public records before drawing conclusions.
Who uses it Election officials, voter-protection volunteers, journalists covering voting access.
The workflow:
Centre on the polling place.
Set radius to 3 mi for urban precincts, 10 mi for suburban precincts, 25 mi for rural precincts (these are the distances at which voter turnout begins to drop measurably in the academic literature on access).
Compare to the actual precinct boundary; gaps identify voters who live inside the precinct but outside the practical radius — the highest-friction voters.
Worked example — Rural Mississippi polling access · 10 mi radius. A 10-mile radius around a Sunflower County, MS polling place misses parts of three neighbouring townships where the assigned precinct site is technically the same building — meaning the farthest-residing voters in that precinct face a 20+ mile round trip on election day, the kind of friction that shows up in single-digit turnout gaps between rural and urban precincts in the same county. Open this radius in the tool →
Common pitfall. Polling-place consolidation between elections is common; rely on the current year’s polling-place locator, not last cycle’s.
Every example above is one click into the Map Radius Tool. The tool reads the centre lat/lng, the radius value, and the unit from the URL hash, so the prefilled examples open at the exact location and zoom level cited in the worked example. To draw your own:
Three failure modes recur across all 25 use cases:
Straight-line versus driving distance. A 30-mile radius in Pittsburgh, Seattle, or San Francisco is a different operational footprint than the same radius in Indianapolis — bridges, hills, and one-way streets change everything. Use the radius for screening, the Drive Time Map for the real answer.
Projection distortion. The circle on the map is geodesic (true distance on Earth); the way it is rendered depends on the map projection. Near the poles, the rendered shape elongates north-south; near the equator, it looks like a perfect circle. The distances are identical in both — the visual is the projection.
Static circle versus dynamic reality. Hurricane cones, wildfire perimeters, and evacuation zones are not symmetric — wind direction and terrain warp them. The radius is the planning baseline; the actual hazard footprint comes from the National Hurricane Center, the relevant CAL FIRE incident page, or local emergency management.
Frequently asked questions
A radius map is a map with a circle drawn around a chosen centre point, used to identify everything (places, populations, distances) within a given straight-line distance of that point.
No. A radius is a circle measured by straight-line (great-circle) distance — every point on the boundary is the same distance from the centre. A drive-time isochrone follows the road network and is almost never a circle; it bulges along highways and shrinks across rivers and mountains. Use a radius for screening and an isochrone for the real-world answer.
The circle is computed as a geodesic (true-distance) polygon on the WGS84 ellipsoid using the haversine formula, accurate to within about 0.5 % at any latitude. It is not a Euclidean circle on a flat Mercator projection, which is why the rendered shape elongates slightly toward the poles.
Yes — the Map Radius Tool encodes the centre, radius, and unit into the URL hash. Copy the URL after you draw and paste it anywhere; whoever opens it sees the same map at the same zoom.
For US-scale work, anything up to a few thousand miles renders cleanly. Above ~6,000 mi the polygon wraps around the world and the projection breaks down; the underlying math still works, but the visualisation stops being useful.
Yes — the tool supports multiple circles, each with its own centre, radius, and label. The shared URL state captures all of them.
There is no single conversion — it depends on the road network and time of day. As a rough planning constant, divide miles by 1 (mile per minute) for major urban driving, by 0.8 for suburban, and by 0.4 for mountainous rural. Use the Drive Time Map for the real answer.
The base map uses Web Mercator, which stretches features near the poles. A radius drawn near Anchorage will look much taller than wide; one drawn near the equator will look nearly perfectly circular. The underlying area and distances are identical — the visual is the projection, not the math.
Yes — the geodesic radius works at any latitude and longitude on Earth. Some companion features (ZIP code lookup, US Census population) are US-only; the radius drawing itself is global.
The radius is a polygon; with most browsers you can save the shareable URL and paste it into a GeoJSON generator. SimpleMapLab’s upcoming geographic-data export will surface this directly. Until then, the Map Area Calculator can ingest a hand-drawn equivalent.
Google Maps does not have a native radius tool. The standard workaround is to use a third-party tool (SimpleMapLab’s Map Radius Tool is one option) and screenshot the result; see our guide "How to draw a radius on Google Maps (free alternative)" for the full walk-through.
It is free, requires no account, and works entirely in your browser. No data is uploaded to any server; the radius math runs locally on the lat/lng you provide.
Related reading
The same tool, applied to a real research question: The 100-Mile Radius Around Every US State Capital — a 50-state ranking of how much of each state's population sits within 100 miles of its capitol building. Per-state pages, downloadable CC-BY 4.0 dataset.