Ask the Expert Question-and-Answer Archive

by Ron Joseph

December, 2009

Amount of Paint Required

Q. "Theoretically" if 100 gal of paint is used with no loss on a job, what would be the actual number of gals required to cover an area at a desired thickness. All that known is the transfer efficiency is set at 75%, 1 gal of paint will cover 1604ft/2 @ 1 mil. Could you show me how to work this out.

Thanks in advance for any help you could provide.

A. The equation is quite simple.

First, please know that 1 gallon of paint that contains absolutely no solvent can cover 1604 ft if it is applied to a dry film thickness (DFT) of 1 mil at a transfer efficiency of 100%. You can get to that number by yourself by using conversion tables for volume.

Convert 1 gallon to cubic feet. Then calculate the area that 1 gallon (or the cubic feet equivalent) will cover if the thickness is 0.001" (1 mil). You should get an answer of 1,604 ft2.

If you want to calculate coverage of any coating:

Coverage (ft2) =          G (gals) x 1604 ft2/gal/mil x 100 x 100
                        DFT (mils) x % Volume solids x % Transfer Efficiency

You can find the % volume solids on most technical data sheets, but will need to guess at the TE.

Good luck,

Ron Joseph