Paint & Walls Calculators

Paint, primer, drywall and wallpaper estimates.

Wall work is estimated from one number, the wall area: perimeter times height minus doors and windows. From that area the calculators here give gallons of paint or primer, sheets of drywall with screws and compound, rolls of wallpaper by pattern repeat, and bags of stucco or plaster.

Coverage figures are the manufacturer's typical values, 350 to 400 square feet per gallon of paint, 32 square feet per 4 x 8 sheet of drywall, 1.25 gallons of joint compound per 100 square feet. Textured walls, bare drywall and dark color changes use more, and each tool has a field for it.

All paint & walls calculators

Paint CalculatorWork out how many gallons of paint you need for a room. Enter the room size, doors, windows and number of coats to get wall, ceiling and total paint quantities.Drywall CalculatorCalculate how many sheets of drywall you need for a room, plus screws, joint compound and tape. Supports 4x8, 4x10 and 4x12 sheets with or without the ceiling.Primer CalculatorCalculate how many gallons of primer you need for a room based on wall area, doors, windows and the surface: painted walls, new drywall, bare wood or a dark color.Ceiling Paint CalculatorCalculate how many gallons of ceiling paint you need from the room size, number of coats and ceiling texture. Popcorn and textured ceilings soak up more paint.Wallpaper CalculatorCalculate how many rolls of wallpaper you need for a room from the wall height, perimeter, roll size and pattern repeat, with strips per roll and strips needed.Crown Molding CalculatorCalculate how many linear feet of crown molding a room needs and how many 8, 12 or 16 ft pieces to buy, with inside and outside corner counts, finish nails and cost.Joint Compound CalculatorCalculate how many gallons and buckets of joint compound you need to tape, finish or skim coat drywall, plus rolls of paper or mesh tape and the weight to haul home.Wall Square Footage CalculatorCalculate the square footage of the walls in a room from its length, width and ceiling height, minus doors and windows, for paint, drywall, wallpaper or tile.Stucco CalculatorEstimate bags of base coat and finish coat stucco, metal lath sheets and building paper for a wall, for a traditional three-coat or a one-coat stucco system.Plaster CalculatorEstimate bags of veneer plaster or gypsum basecoat, blueboard or lath, and mixing water for a wall, with coverage for skim coat, basecoat and two-coat plaster.Paint Cost CalculatorEstimate what it costs to paint a room: gallons of paint and primer to buy, material cost, optional pro labor per square foot and the cost per square foot of wall.

A typical project, in order

Carry each result into the next tool.

1Wall Square Footage CalculatorWall area minus openings, used by every tool below
2Drywall CalculatorSheets, screws, compound and tape
3Joint Compound CalculatorBuckets for taping or a skim coat
4Primer CalculatorSeal new drywall or a color change
5Paint CalculatorGallons for the walls
6Ceiling Paint CalculatorFlat paint for the ceiling
7Paint Cost CalculatorMaterials and labor budget

Paint & Walls questions

How much paint do I need per square foot of wall?

About 1 gallon per 350 to 400 square feet per coat. A 12 x 12 room with 8 ft ceilings has roughly 334 square feet of wall after openings, so 2 gallons for two coats.

Do I subtract doors and windows from wall area?

Yes. Deduct about 20 square feet per door and 15 per window. On a wall with a large picture window or patio door, deduct its actual size.

How many sheets of drywall for a room?

Total surface area (walls plus ceiling) divided by 32 for 4 x 8 sheets, plus 10% waste. A 12 x 12 room with an 8 ft ceiling takes about 17 sheets.