<?php

/**
   NAME        : convert_from_bytes()
   VERSION     : 1.0
   AUTHOR      : J de Silva
   DESCRIPTION : returns FLOAT value; handles converting
                 bytes to values in units between
                 'bits' and 'gigabytes'.
   TYPE        : function
   ======================================*/

function convert_from_bytes( $bytes, $to=NULL )
{
  $float = floatval( $bytes );
  switch( $to )
  {
    case 'Kb' :            // Kilobit
      $float = ( $float*8 ) / 1024;
      break;
    case 'b' :             // bit
      $float *= 8;
      break;
    case 'GB' :            // Gigabyte
      $float /= 1024;
    case 'MB' :            // Megabyte
      $float /= 1024;
    case 'KB' :            // Kilobyte
      $float /= 1024;
    default :              // byte
  }
  unset( $bytes, $to );
  return( $float );
}
?>

<?php
// let's say we have a dummy byte size to convert
$filesize = 3670016;  // bytes


// if we need to convert this bytes to KB (kilobytes)
$KB = convert_from_bytes( $filesize, 'KB' );
  // $KB == 3584

// if we need to convert these bytes to MB (megabytes)
$MB = convert_from_bytes( $filesize, 'MB' );
  // $MB == 3.5

// if we need to convert these bytes to b (bits)
$b = convert_from_bytes( $filesize, 'b' );
  // $b == 29360128
?>