Click wherever the circle should start. Circle is already selected, so you can go straight in.
Click again and drag to the size you want, or just tap a preset. The km/mi toggle switches both.
Copy a link, send it to the printer, or pull the shape out as GeoJSON. Stack more circles to compare.
Here’s the thing people get wrong about radius maps. Area grows with the square of the radius, so going from 5 km to 10 km doesn’t double what you’ve covered. It quadruples it. That’s the reason a circle on a map tells you something a distance figure never will, and it’s why the jump from a 25 km ring to a 50 km one is so much bigger than it looks on screen.
| Radius | Area (km²) | Same radius in miles | Area (mi²) |
|---|---|---|---|
| 1 km | 3.14 | 0.62 mi | 1.21 |
| 5 km | 78.54 | 3.11 mi | 30.32 |
| 10 km | 314 | 6.21 mi | 121 |
| 25 km | 1,963 | 15.53 mi | 758 |
| 50 km | 7,854 | 31.07 mi | 3,032 |
| 1.61 km | 8.14 | 1 mi | 3.14 |
| 8.05 km | 203 | 5 mi | 78.54 |
| 16.09 km | 814 | 10 mi | 314 |
| 40.23 km | 5,085 | 25 mi | 1,963 |
| 80.47 km | 20,342 | 50 mi | 7,854 |
Worth watching if you switch units mid-job. A mile is 1.609344 km, so swapping a 50 km ring for a 50 mile one quietly hands you about 2.59 times the ground.
Every circle here is a straight-line radius. Same real distance from the centre, whichever way you head out. If your question is about coverage, that’s what you want: how far a delivery run reaches, which schools sit within 5 km of a house, how far a festival’s noise carries.
Travel time is another matter. A 20-minute drive is a lopsided blob, an isochrone, that races down the motorway and stops dead at the river. Drawing one properly means routing over a road network on a server. We don’t have one, on purpose, because the whole site runs in your browser with no account and nothing to sign up for.
So use the circle as your outer bound and treat it as a first pass. Actual travel distance out to the edge always beats the radius. In a town laid out on a grid, reckon on 20–40% more. Stick a harbour or a decent hill in the way and that figure stops meaning much at all.
Distances here are great-circle distances, measured across the surface of the globe. Not a line drawn on the flat map image, which is where a lot of simpler tools quietly go wrong. What you see is really a many-sided polygon, with every corner sitting the chosen distance from your centre point, and the area gets measured on the globe too.
Push a circle north or south and it stretches. Mercator has to pull east–west distance apart to keep the map a neat rectangle, so something genuinely round on the ground has no way of staying round on your screen. A 50 km circle over Reykjavík looks vastly wider than the same 50 km over Nairobi. They’re the same circle.
One shortcut worth admitting to: we treat the Earth as a sphere, and it’s really a slightly squashed one. That costs you a fraction of a percent, far less than the width of the line you’re looking at. Fine for catchments and coverage. Not a surveying instrument, so don’t settle a boundary dispute with it.