Room Paint Calculator

Enter your room size, doors and windows to see how much wall and ceiling paint to buy.

How the calculation works

wall area = 2 × (length + width) × height − 21 sq ft per door − 15 sq ft per window

The wall area times the number of coats, divided by coverage, gives gallons. The result is rounded up to the nearest quart, because many stores sell quarts. The ceiling is the floor area, with two coats assumed.

Worked example

A 14 × 12 foot room with 8 foot walls has 416 sq ft of wall. Take away one door and two windows, and 365 sq ft remain. Two coats at 350 sq ft per gallon need 2.1 gallons, so buy 2 gallons and 1 quart. The 168 sq ft ceiling needs about 1 gallon of ceiling paint for two coats.

Tips

• Prime first over new drywall, patches, stains, or when going from dark to light. Primer counts as a coat for coverage.
• Buy all the paint at once, or mix (box) the cans together in a bucket. Separate batches can differ slightly in color.
• Keep a little extra for touch-ups, labeled with the room and date.

Frequently asked questions

How much paint for a 12 × 12 room?

With 8 foot walls, one door and one window, there are about 348 sq ft of wall. Two coats need about 2 gallons.

Is one coat of paint enough?

One coat can be enough when repainting the same color with good paint. For a color change, or for even sheen, plan on two.