How much paint for a 18 × 20 ft room?
Painting the four walls of a 18 × 20 ft room with 8 ft ceilings in two coats takes about 3.6 gallons of paint — round up to 4 one-gallon cans. That is 575 sq ft of wall at 350 sq ft per gallon per coat, with one door and window deducted and a 10% loss allowance.
- Room
- 18 × 20 ft, 8 ft walls
- Wall area
- 575 sq ft
- Coats
- 2
- Paint needed
- 3.6 gal
Based on 350 sq ft per gallon per coat, two coats, 8 ft walls, a 10% loss allowance, and one standard door and window deducted. Walls only — ceiling paint is separate.
Change the numbers in the paint calculator →How this is worked out
Paint calculator uses the same method as every tool here: measure the area, add a visible allowance, divide by what one can covers, and round up. The number above is the honest planning quantity — not an exact coverage guarantee. Coverage varies with colour and surface.
paint = wall area × coats ÷ coverage × (1 + loss) → round up to whole cans
Other sizes
Related
- Paint calculator — change any number for your job
- Room material planner — every material on one shopping list
- How much does a gallon of paint cover?
- Floor area is not paintable area
Frequently asked questions
How many gallons of paint for a 18 × 20 room?
About 3.6 gallons for two coats on the walls of a 18 × 20 ft room with 8 ft ceilings — round up to 4 one-gallon cans. Wall area is about 575 sq ft.
Is the ceiling included?
No. This is wall paint only. Ceiling paint is estimated separately — add the ceiling in the paint calculator or room planner.
How much for one coat?
Roughly half — set coats to 1 in the paint calculator to see the exact figure for this room.