Paint Calculator
Enter the room's length, width and wall height. The calculator works out the wall area, takes off the doors and windows, and tells you how much paint to buy.
Type a number and the answer appears straight away.
Paint needed2.18 gallonsBuy 3 gallons
- Wall area to paint
- 381 sq ft
- Total over 2 coats
- 762 sq ft
- In gallons and quarts
- 2 gal 1 qt
- Liters
- 8.2
Rough or unprimed surfaces soak up more paint, and a strong colour change may need a third coat or a primer.
The math behind it: Paint
gallons = (wall area - doors - windows) x coats / coverage per gallon
A 12 ft by 15 ft room with 8 ft walls, one door and two windows has 381 square feet of wall to paint. Two coats at 350 square feet per gallon take 2.18 gallons, so buy 3 gallons, or 2 gallons and a quart.
Common questions
How much paint do I need for a room?
A typical 12 ft by 15 ft bedroom needs a little over 2 gallons for two coats on the walls. As a rule, one gallon covers about 350 square feet.
How many square feet does a gallon of paint cover?
About 350 to 400 square feet on smooth, primed walls. Rough, textured or unpainted surfaces absorb more, so expect less.
Do I need two coats of paint?
Usually, yes. Two coats give an even colour and a tougher finish. One coat can be enough when repainting in the same colour with good quality paint.
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