class.upload.php is a powerful and mature PHP class to manage uploaded files, and manipulate images in many ways. The script is available under a GPL license.
more info about the class
See all posts See thread Reply
< input type="hidden" name="MAX_FILE_SIZE" value="500" />
On traditional upload forms, you can use MAX_FILE_SIZE:
But if you use XMLHttpRequest (the last version of the class supports this), you can check the size via JS.