Home Project CalculatorsMeasure. Calculate. Make a plan.

PRACTICAL HOME PROJECT MATH

Paint calculator

Estimate paint for rectangular room walls, allowing for openings, coats and product coverage.

Rectangular room, walls only. Replace the example coverage with the value on your paint label. Allowance is your choice.

YOUR PLANNING ESTIMATE

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Enter your measurements

See the calculation

The calculation

Wall area = 2 × (length + width) × height − openings. Multiply by coats, divide by coverage per gallon, then apply your extra allowance.

A worked example

A 12 × 10 ft room with 8 ft walls has 352 sq ft of wall area. Subtract 40 sq ft of openings: 312 sq ft. Two coats at 350 sq ft per gallon with 10% extra need about 1.96 gallons, rounded up to two one-gallon cans.

Before buying

Read the paint label. Texture, porosity and color changes can affect coverage. This estimate excludes ceilings, primer and trim. For multiple rooms, calculate each separately before combining quantities.