Radius map

How to use it

1. 1

   Pick the center

   Type an address, a town or a place. You can also use your location, click on the map or drag the center of the circle.

2. 2

   Set the radius

   Type a number, drag the slider, tap a quick value or drag the edge of the circle on the map. It goes up to 12,400 miles, in miles or kilometers.

3. 3

   Add more and style them

   Add circles one by one or paste a list with many of them (up to 100). Give each one a label, its own color, fill opacity and outline width.

4. 4

   Read the result and share it

   You’ll see the area, the perimeter, the states and counties it touches and how many people live inside. Copy the link: whoever opens it sees the same circles, styled the same way.

What it’s for

• Delivery areas

  Paste the list of your stores or warehouses with each radius and show customers how far you deliver, with a color for each area.

• House hunting

  Put the center on your workplace or your kid’s school, drag the edge out to a distance that works for you and see which towns fall inside.

• Trips and travel

  See which cities, parks and lakes are within reach, or how far 1,000 miles from home really goes.

• Geography class

  Teach scale and area with something students can see: 100 mi around downtown Kansas City covers about the same as Maine (30,845 mi²).

100 mi around downtown Kansas City

A circle with a 100 mi radius centered on downtown Kansas City covers 31,414 mi²: about the same as Maine (30,845 mi²). Its edge is 628.3 mi long and it’s 200 mi across.

It reaches into three states (Kansas, Missouri and Nebraska) and 73 counties. A state or county counts as soon as the circle reaches into it, even if it doesn’t cover all of it.

About 3.16 million people live inside it, with 516 ZIP codes and 518 cities and towns. The “What’s inside this circle?” panel works it out with the same method as “Population in a radius”.

Many circles at once

With “Add many at once” you paste a list, or upload a CSV or TXT file, with one circle per line: the center (an address, a place or coordinates), the radius and a label. You can draw up to 100 circles.

address,radius,label,color
"1600 Pennsylvania Ave NW, Washington",5 mi,Head office,green
"38.8977, -77.0365",2 mi,Warehouse,#2F7AA6
"Arlington, VA",3 km,South route,red

Places and coordinates are found instantly. Addresses are looked up with Photon (or CartoCiudad, in Spain) one at a time, about one per second, so as not to overload those public services. You can stop whenever you like, and any line that fails is listed on its own.

The CSV file the tool downloads can be loaded back as is, with its styles and labels.

Very large circles

The radius goes up to 12,400 miles, almost halfway around the Earth. The circle is still drawn on the Earth itself, even when it crosses the 180th meridian or has a pole inside, and once the radius is more than a quarter of the way around (about 6,200 miles) it holds both poles: what’s left outside is a cap around the antipode of the center.

For example, 3,000 miles around downtown Kansas City covers 26,946,853 mi², 13.7% of the Earth’s surface: 48% of all the land on Earth (56,686,280 mi²).

How it’s calculated

All Map Tools draws the circle on the Earth itself: every point on the edge is the same real distance from the center, measured on the WGS84 ellipsoid, which is why it looks a little stretched toward the poles on the map. There are two ways to work out the area.

All Map Tools uses the sphere formula, because it matches the circle you see on the map. For 100 mi it gives 31,414 mi², almost the same as on a plane; the gap grows with the radius: at 500 mi, 784,355 mi² versus 785,398 mi² (0.1% less).