Zip Code Radius PHP Scripts

[Historical Forums User]

I’m looking for a very simple (free) script for doing a zip code radius search.

A user will input a zip code into a form field. I then need to check that provided zip code with a mysql database table of programs (which will have zipcode or lat/long, whatever needed, and only display those within 45 miles of the provided zip code.

So essentially I just need help generating a mysql query and doing the math. I’ve been referenced to the greatest circle distance method but I’m having trouble translating it.

Anybody have any good resources on this?

[Democritus]

Because zip codes are on the globe, which is a sphere (i’m told), a circle distance won’t quite do it. Your problem is in 2 parts, and while I won’t just give you the code, I can tell you how to solve it.

First, you need to convert the zip codes to latitudes and longitudes. I suggest using the google geocoder. Once you have all of your codes in latitudes and longitudes, when a user enters their zip code, you need to convert that to a latitude and longitude as well.

Then, to find the distance, you need to use a formula called the haversine formula. It can take 2 latitudes and longitudes and give you the distance between them. So your sql should just get all zips where that distance is less than whatever you want.

Good luck,
-D

[Historical Forums User]

Thanks. I have found a script online that’s helped me solved this.

Thanks for the explanation.

[Author]

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