How much paint do I need for a room?

Short answer

One gallon covers about 350 to 400 square feet per coat on smooth, primed walls. Add the widths of all walls, multiply by the ceiling height, subtract about 20 square feet per door and 15 per window, then divide by 350 and multiply by the number of coats. A typical 12 by 12 foot bedroom takes about 2 gallons for two coats.

Worked example

A 12 by 14 foot room with 8 foot ceilings: (12 + 14 + 12 + 14) x 8 = 416 square feet. Subtract one door and two windows (50) = 366 square feet. Two coats = 732 square feet, or just over 2 gallons. Buy 2 gallons plus a quart, or a 5 gallon bucket for several rooms of the same color.

Buy more for

Textured, rough or unprimed surfaces
Deep colors that need extra coats
Exterior siding, especially rough cedar
Touch-ups later (keep a labeled quart)

Want a pro to handle it?

Get quotes from up to five local painters. Free.

Start my project

Still picking colors?

Build a palette that goes together and see it on a room or house.

Open Color Studio

Updated September 2026. Always follow the directions on your product's label; manufacturer instructions come first.