Functions used to convert 64bit Steam ID to 32bit and the other way around.

steamid_conversion.php

<?php

function convert_steamid_64bit_to_32bit($id)
{
  $result = substr($id, 3) - 61197960265728;
  return (string) $result;
}

function convert_steamid_32bit_to_64bit($id)
{
  $result = '765'.($id + 61197960265728);
  return (string) $result;
}

$sixtyfour = '76561197992765754';
$thirtytwo = '32500026';

var_dump(convert_steamid_32bit_to_64bit($thirtytwo) === $sixtyfour); // bool(true)
var_dump(convert_steamid_64bit_to_32bit($sixtyfour) === $thirtytwo); // bool(true)

wow so simple thanks, also how did you get the base number? like what was your source? just out of curiosity.

Very useful! I'd also be interested to know what your source was, if you can remember.

Awesome stuff +1

Doesnt work. It produces a false number converting 32 to 64.

I was testing this on Xampp for Windows and it didn't worked. I'm guessing that this have something to do with the unavailability of the 64-bit version of both Xampp and PHP for Windows. I'll test this on a Linux to see if the result is right.
Thanks in advance!

@danfsd, this was intended for 32-bit PHP environments and that unavailability was the reason I created this.

Would you happen to know a direct relation for Group ID as well?

Thanks! you saved much time for me