County Maps US

Tools Radius and county dataUS only

Population Within a Radius

For market sizing and catchment areas. The total is a sum of ZIP Code Tabulation Areas whose centre falls in the circle, and the method is stated on the page.

How to use it

  1. Type a centre, use your location, or click the map.
  2. Set the radius. Three miles and up gives a stable figure; below that too few ZIP areas fall inside.
  3. Press "Count population" for the total, the circle area, the average density and the list of ZIP areas counted.
  4. Download the ZIP list as CSV to show your working.

How it works

Every ZIP Code Tabulation Area whose centre point lies inside the circle is counted in full, using the ACS 2020-2024 five-year population estimate for the ZCTA. Areas whose centre is outside are not counted at all, even if part of them is inside. The two errors tend to cancel over a radius of several miles but not for a small circle in a city with large ZIPs.

This is a centroid method, not an area-weighted overlay. A block-level overlay would be more precise but needs geometry that does not fit in a browser page. Treat the total as an estimate good to within roughly ten percent for radii of five miles and more in urban areas, and looser in rural ones.

Questions

How accurate is the population within a radius?
It is an estimate. Whole ZIP areas are counted or skipped by where their centre falls, so the total can be off by the population of one or two ZIP areas at the edge. At a 10-mile radius in a metropolitan area that is usually a few percent; at 2 miles it can be much more.
Which year is the population?
The American Community Survey five-year estimate for 2020 to 2024, the most recent population published for ZIP Code Tabulation Areas. There is no yearly estimate for ZIPs.
Can I count population by driving time instead of distance?
Not with this tool. The drive-time tool draws the area you can reach in a set number of minutes; you can compare its shape with the circle here, but the count is by straight-line radius only.

All map tools, free and without an account. Location data is processed in your browser and by the open geocoding services named on the sources page; nothing is stored by this site.