How much paint do I need for a 12×12 room?

The short answer, then the math so you can check it for your room.

About 2 gallons for the wallsThat's for two coats in a 12×12 room with 8-foot ceilings, one door and two windows. Add about 1 gallon of ceiling paint if you're doing the ceiling too.

Step 1: Find the wall area

Add up the length of all four walls to get the perimeter, then multiply by the ceiling height.

12 + 12 + 12 + 12 = 48 feet of wall. 48 × 8 feet high = 384 sq ft.

Step 2: Subtract doors and windows

A standard interior door is about 21 sq ft and an average window is about 15 sq ft. With one door and two windows:

384 − 21 − 15 − 15 = 333 sq ft to paint.

Step 3: Multiply by coats, divide by coverage

Most interior paint covers 350 to 400 sq ft per gallon. Use 350 to be safe. Two coats is standard, especially when you're changing color.

333 × 2 coats = 666 sq ft. 666 ÷ 350 = 1.9 gallons, so buy 2.

Quick reference for 12×12 rooms

Ceiling height	Wall area to paint	2 coats	Buy
8 ft	333 sq ft	1.9 gal	2 gal
9 ft	381 sq ft	2.2 gal	3 gal (or 2 gal + 1 qt)
10 ft	429 sq ft	2.5 gal	3 gal

Assumes one door and two windows, 350 sq ft per gallon.

What about the ceiling?

A 12×12 ceiling is 144 sq ft. Two coats is 288 sq ft, which is just under 1 gallon of ceiling paint.

When to buy more

Buy extra if the walls are textured or unprimed drywall, if you're covering a dark color with a light one, or if you want some left over for touch-ups. In those cases coverage can drop closer to 250 to 300 sq ft per gallon.

What you'll need

Interior paint · Roller kit · Painter's tape · Drop cloth

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