How the Paint Quantity Calculator Works
Our paint calculator uses standard industry measurements to give you a precise estimate. We calculate the total surface area of your walls (Length × Height + Width × Height) × 2, and then subtract the standard area for doors (20 sq. ft.) and windows (15 sq. ft.). Finally, we divide by 350 (average coverage per gallon) and multiply by the number of coats needed.
Why Accurate Paint Estimates Matter
Buying too much paint is a waste of money, while buying too little disrupts your workflow. In the USA, the average gallon of quality interior paint costs between $30 and $60. Getting a precise estimate helps you budget effectively for your home improvement project.
Frequently Asked Questions
Does this include the ceiling?
No, this calculation is for walls only. If you plan to paint the ceiling, calculate its area (Length × Width) separately. Usually, one gallon is enough for a standard room ceiling.
How much does 1 gallon cover?
On average, one gallon of paint covers 350 to 400 square feet of smooth wall surface. Textured walls may require more paint.