Yardstickly

Paint guide

How Much Paint Do I Need for a Room? Chart by Room Size

A 12 × 12 ft room: about 2 gallons for two coats.

Reviewed by , Editor. Last reviewed . Figures are calculated with the same formulas as our calculators.

A paint roller putting white paint on a wall
Two coats is the norm; a big colour change can need a third.

A 12 × 12 ft room with 8 ft walls, one door and two windows has about 333 sq ft of wall. Two coats at 350 sq ft per gallon need 1.9 gallons, so buy 2 one-gallon cans. Add the ceiling and it's 2.7 gallons.

Working out the wall area of a room to paintThe four walls of a 12 by 12 foot room laid out flat: 48 feet of wall, 8 feet high, is 384 square feet, less 21 for a door and 15 for a window, leaving 348 square feet per coat.wall 1: 12 ftdoorwall 2: 12 ftwall 3: 12 ftwindowwall 4: 12 ft8 ftPerimeter × height − doors − windows48 ft × 8 ft = 384 sq ft − 21 (door) − 15 (window) = 348 sq ft per coat
Unfold the room: perimeter × height gives the wall area. Take off about 21 sq ft (1.9 m²) per door and 15 sq ft (1.4 m²) per window, then multiply by the coats.

Paint for common room sizes

Walls only, 8 ft ceilings, one door and one window, two coats at 350 sq ft per gallon
RoomWall areaPaint neededCans to buy
10 × 10 ft284 sq ft1.6 gal2 × 1 gallon
10 × 12 ft316 sq ft1.8 gal2 × 1 gallon
12 × 12 ft348 sq ft2 gal2 × 1 gallon
12 × 14 ft380 sq ft2.2 gal2 × 1 gallon + 1 × quart
14 × 16 ft444 sq ft2.5 gal3 × 1 gallon
16 × 20 ft540 sq ft3.1 gal1 × 5 gallon

Sherwin-Williams says a gallon typically covers about 350–400 sq ft per coat. We use the low end, because textured or porous walls take more. Cans are chosen to cover the need with the least waste, from quarts, gallons and 5-gallon pails.

Metric: walls only, 2.4 m ceilings, one door and one window, two coats at 10 m² per litre
RoomWall areaPaint neededUK tinsAustralian tins
3 × 3 m25.5 m²5.1 L1 × 5 L + 1 × 1 L1 × 4 L + 2 × 1 L
3 × 4 m30.3 m²6.1 L1 × 5 L + 1 × 2.5 L1 × 10 L
4 × 4 m35.1 m²7 L1 × 5 L + 1 × 2.5 L1 × 10 L
4 × 5 m39.9 m²8 L1 × 10 L1 × 10 L
5 × 6 m49.5 m²9.9 L1 × 10 L1 × 10 L

Metric tins state their own coverage, often between 10 and 16 m² per litre. Dulux UK's advice is to use the figure on the tin; enter it in the calculator for an exact count.

Worked example: a 12 × 12 ft bedroom

  1. Perimeter: 12 + 12 + 12 + 12 = 48 ft. Wall area: 48 × 8 = 384 sq ft.
  2. Take off one door (about 21 sq ft) and two windows (about 15 sq ft each): 333 sq ft.
  3. Two coats: 666 sq ft of painting.
  4. At 350 sq ft per gallon: 1.9 gallons, so 2 × 1 gallon.

When to buy more

  • Big colour change: going from dark to light, or onto new plaster or drywall, often needs a primer coat or a third coat.
  • Rough surfaces: textured walls and masonry can take 20% more.
  • Touch-ups: keep a little from the same batch for later.

Sources

  1. Sherwin-Williams: Paint calculator
  2. Dulux UK: How much paint do you need?