Paint Calculator: How Much Paint Do I Need
Work out how much paint a project needs. Enter the wall area, or a room's length, width and wall height, then subtract doors and windows to see gallons.
How to estimate paint for a room
- Enter the room length, width and wall height, or a known wall area.
- Set the number of coats, doors and windows, and your paint coverage.
- Read off the paintable area and the gallons you need to buy.
Examples
12 by 12 ft room, 8 ft walls, 2 coats
L 12, W 12, height 8, 1 door, 2 windows, 2 coats
333 sq ft paintable, 666 sq ft to cover, 2 gallons
Frequently asked questions
How much area does a gallon of paint cover?
A gallon covers roughly 350 square feet per coat on smooth, primed walls. Rough, porous or unprimed surfaces soak up more, so coverage drops and you may need extra.
How many coats of paint should I plan for?
Two coats is the standard for an even, durable finish. One coat can work over a similar color, while bold or drastic color changes may need a primer plus two coats.
Do you subtract doors and windows?
Yes. The calculator removes about 21 square feet per door and 15 square feet per window from the paintable area, since you do not paint those openings.
Should I round up when buying paint?
Yes. Paint is sold in whole gallons, so the result is always rounded up. Buying a little extra also gives you paint for touch ups later.
Does this include the ceiling?
No. The estimate covers walls only. To paint the ceiling, add its area (length times width) to the wall area field and recalculate.
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