$re = '/(((\d{4,}(?:[\.,]\d+)?)|((\d{1,3}(?:((\.)|,)\d{1,3})?(?:\6\d{1,3})*(?:(?(7),|\.)\d+)?)))\s*(?:[a-zA-Z]*))/m';
$str = '123mm
123mm
123 mm
123 mm
123MM
123MM
123 MM
123 MM
123,45mm
123.45mm
123,45 mm
123.45 mm
123,45MM
123.45MM
123,45 MM
123.45 MM
1.234,56mm
1,234.56mm
1.234,56 mm
1,234.56 mm
1.234,56MM
1,234.56MM
1.234,56 MM
1,234.56 MM
4.321.234,56mm
4,321,234.56mm
4.321.234,56 mm
4,321,234.56 mm
4.321.234,56MM
4,321,234.56MM
4.321.234,56 MM
4,321,234.56 MM
4.321,234.56mm
4,321,234,56mm
4.321.234,56 mm
4,321.234.56 mm
4.321.234,56MM
4.321,234.56MM
4.321.234,56 MM
123,499,321,234.56 MMillimeter George Washington
123456.23mm
123456,23mm
123456..23mm
123456.,23mm
123,456,789.23
1.234,56MM 1,234.56MM 1.234,56 MM ,234.56 MM Alabama
4.321.234,56mm 4,321,234.56mm 4.321.234,56 mm 4,321,234.56 mm South Africa';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php