Paint Coverage Calculator

Direct answer

Paint needed is the measured surface area times the number of coats, divided by the labelled coverage per litre, with any chosen waste allowance added. Behr’s calculator labels its results as estimates and shows that product coverage can vary, so enter the coverage from the specific paint label.

Variables and formula

• Surface area: area to coat after any exclusions.
• Product coverage: labelled square metres per litre for one coat.
• Coats and waste: the planned number of coats and a transparent allowance.

Paint litres = Area × Coats / Coverage per litre × (1 + Waste allowance)

Reproducible example

For 50 m², two coats, 10 m²/L coverage and 10% allowance: 50 × 2 / 10 × 1.10 = 11 L.

Interpretation

Round the estimate to an available container size only after checking the product label. The result is a planning quantity, not a promise of finish quality or exact material use.

Assumptions and limitations

• The surface is measured in square metres and coverage is for the same product and coat.
• Porous or textured surfaces can require more paint.
• Doors, windows, primer and trim are excluded unless included in the area or allowance.

Common mistakes

• Treating one-coat coverage as a universal value.
• Forgetting to multiply by the number of coats.
• Adding a waste allowance twice.

Assumptions

• The coverage value is taken from the specific product label.
• Surface condition, application method and opacity can change actual use.

Sources and methodology

CalcMotive publishes the formula and assumptions so you can decide whether the estimate fits your use case. See our methodology standards.

• Interior & Exterior Paint Coverage Calculator; Behr; accessed Jul 27, 2026