ZIP Code Radius

What is the purpose of computing the number of ZIP codes in a radius and how is it done?

A common use for a ZIP code database is calculating all the ZIP codes in a radius. ZIP code radius searches can be very helpful when creating applications such as nearest store or vendor finders. While this type of search is a very common request, many people do not understand why a ZIP code radius search is helpful.

A radius is the length of a line segment between the center and circumference of a circle. What that means is that if you were to take the center of a ZIP code and draw a circle around it, all the ZIP codes that are inside that circle are inside the ZIP code radius.

To find the ZIP code radius, you need to know the latitude and longitude for each ZIP code. Many ZIP code databases will include this information (usually based on the center of the ZIP code).

For a user to conduct a ZIP code radius search, he or she will need to know the ZIP code that they are interested in and the number of miles he or she would like to search. Here is a sample of results from a 5 mile ZIP code radius search on the free zip code lookup at ZIP code download. It is not the complete results, but should give you an idea of what a ZIP code radius search will provide.

ZIPCode	Miles	City	State	Latitude	Longitude
98685	1.55	Vancouver	Washington	45.709089	-122.681254
98686	2.39	Vancouver	Washington	45.717060	-122.633301
98663	2.63	Vancouver	Washington	45.652447	-122.656498
98668	2.69	Vancouver	Washington	45.721072	-122.630742
98660	3.31	Vancouver	Washington	45.642953	-122.675812
98666	3.60	Vancouver	Washington	45.712413	-122.597049

For developers, programming apis, such as the Radius Assistant from ZIP code download, can be very helpful when creating software and applications that need radius searches.