Can anyone confirm them for me?

Iv read that professional rings should be no less than 16 squared foot and no larger than 20 squared feet, usa and olymic are to be no less than 18 squared feet and no more than 24 squared feet?

but 20ft square seems very small, that would be like 5ft by 4 ft? surly thats not right?

thanks alot in advance for the answers