Practical Uses for a Radius Map (With Worked Examples)
By Marko Visic·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: 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.
Once you have a radius tool open, a surprising amount of life decisions get easier — where to live, where to work from, where to meet, how far is too far from the people who matter. Common life-planning radius problems.
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.
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.
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, two Green Line T stations, an independent bookstore, four pharmacies, the public high school, and a 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, hospital reach, and voting precincts are radii drawn against the clock — or against the calendar. The radius is the planning baseline against an official boundary or service standard.
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.
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 rural Mississippi polling place can miss outlying areas where the assigned precinct site is the same building several miles away — 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 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.
Drone pilots, ham operators, anglers, and day-hikers each have a discipline-specific radius they live inside. The legal or physical reality of the radius matters more than the visualisation.
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.
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:
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.