To avoid having too much leftover wall paint, use these formulas to determine how much paint to buy when you start your home improvement painting project.

Total Wall Area:

[Total Length of All Walls] × [Wall Height] = Total Wall Area

Unpainted Areas:

[Window Height] × [Window Width] × [Number of Windows] = Window Area

[Door Height] × [Door Width] × [Number of Doors] = Door Area

Paintable Wall Area:

[Total Wall Area] – [Window Area] – [Door Area] = Paintable Area

Paint to Order:

[Paintable Area] ÷ 350 = Number of Gallons Needed for Smooth Walls

[Paintable Area] ÷ 300 = Number of Gallons Needed for Rough, Textured Walls or Unpainted Wallboard