How to Calculate How Much Paint You Need
Estimating the right amount of paint is crucial. Too little, and you're making an extra trip to the store. Too much, and you've wasted money. Our calculator simplifies this, but here’s the formula behind the magic:
1. Calculate Total Wall Area
First, find the perimeter of your room by adding all the wall lengths together. Then, multiply the perimeter by the wall height. For a standard rectangular room, the formula is: (2 x Length + 2 x Width) x Height.
2. Subtract Doors and Windows
You don't paint over openings, so we subtract their area. A standard door is about 21 square feet, and a window is about 15 square feet. Our tool does this automatically based on the number of each you enter.
3. Determine the Number of Gallons
A single gallon of paint typically covers about 350-400 square feet. For a quality finish, especially over a darker color, you'll need at least two coats. Our calculator uses a conservative 350 sq. ft. estimate and multiplies by your desired number of coats, then rounds up to the nearest whole gallon.