How large a surface area in units of square feet will 1 gall
     How large a surface area in units of square feet will 1 gallon of paint cover if we apply a coat of paint that is 0.1 centimeter thick? 
  
  Solution
Square feet (surface area) is a two-dimensional unit. Gallons (volume) is a three-dimensional unit. They are completely different, and there is no way to convert between them.
 
 However, if you meant cubic feet (volume), then the following conversions are true:
 
 1 cubic foot = 7.48051945 US gallons
 1 US gallon = 0.133680556 cubic feet

