Painting guide
How Much Paint Do I Need for a Bedroom?
Estimate bedroom wall paint from room dimensions, openings, coat count, coverage, and a small touch-up buffer.
Short answer
For a simple bedroom, calculate wall area from perimeter times wall height, subtract large doors and windows, multiply by coats, add a small buffer, then divide by the paint can's stated coverage and round up to full gallons.
Use the Paint CalculatorThe formula
- Bedroom wall area = 2 x (room length + room width) x wall height
- Paintable wall area = bedroom wall area - large doors and windows
- Coverage needed = paintable wall area x coats x (1 + buffer percentage)
- Gallons to buy = coverage needed / coverage per gallon, rounded up
Worked example
A 12 ft by 10 ft bedroom with 8 ft walls
- Wall area before openings: 2 x (12 + 10) x 8 = 352 sq ft.
- Subtract 20 sq ft for a door and 15 sq ft for one window: 352 - 35 = 317 sq ft.
- Two coats plus a 10% touch-up buffer: 317 x 2 x 1.10 = 697.4 sq ft.
- At 350 sq ft per gallon: 697.4 / 350 = 1.99 gallons.
Buy 2 gallons for the bedroom walls, then estimate ceiling, trim, primer, and repairs separately.
Bedroom paint is based on wall surface
A bedroom's floor area is not the same as its paintable wall area. Start with the room perimeter, multiply by wall height, and then subtract larger openings that materially reduce painted surface.
Closets, accent walls, built-ins, sloped ceilings, and wall repairs can change the estimate. Break unusual rooms into wall-by-wall rectangles when the simple perimeter method stops matching the shape.
Coats usually decide whether one gallon is enough
Sherwin-Williams notes that a gallon typically covers about 350 to 400 square feet, but product, surface condition, and application method affect coverage. A bedroom that seems close to one gallon for one coat can quickly become two gallons when two coats and touch-up paint are included.
Dark-to-light color changes, patched walls, porous surfaces, and new drywall can need primer or additional coats. Keep primer and trim paint separate from the wall-paint estimate.
- Use the coverage on the exact paint product.
- Count each coat across the paintable wall area.
- Keep a labeled leftover amount for bedroom touch-ups when practical.
Use the calculator when the room is not standard
The paint calculator lets you change room size, openings, coats, coverage, and buffer percentage without rebuilding the arithmetic. Use it for bedrooms with several windows, taller walls, closets, or a ceiling that needs separate planning.
References and verification
Use these references together with the instructions and coverage or yield information on the product you select.