I am building more drawers for cabinets in my shop. The drawers are 16.5 inches wide by 22 inches deep. Some will be 6 inches high (5.5 usable with 1/4 inch bottom; 5 usable with 1/2 inch bottom).

Some of the drawers will have heavy items (marbles, ball bearings, etc.). Others will have lighter stuff like pen & pencil hardware, bottle stopper hardware, ...

I would like to use the thinnest bottom that I can and still carry the weight without any sagging.

Is there a rule as how to determine the thickness of a bottom considering the amount of weight the drawer will carry?