Measure the width and height of each opening individually and subtract the exact square footage. Step 3: Account for Multiple Coats
Multiply the width of each wall by the room's height (e.g., a
If painting the ceiling, multiply the room's length by its width. Step 2: Subtract "Unpaintable" Areas how to calculate how much paint to buy for interior
Calculating exactly how much paint to buy prevents unnecessary costs and reduces waste. The general rule of thumb is that with a single coat . Step 1: Calculate Total Wall Surface Area
Subtract approximately 20 to 21 square feet per door. Measure the width and height of each opening
For a faster calculation, measure the entire perimeter of the room (add the lengths of all walls) and multiply it by the ceiling height.
Subtract approximately 15 square feet per window. The general rule of thumb is that with a single coat
You don't need to paint windows, doors, or large fixtures, so subtract their square footage from your total.