HomeMojo · Free calculator

Paint calculator: estimate how much you need

Calculate rectangular wall area from width and height, or enter a known total. Subtract openings and estimate paint using your product’s coverage, coats and chosen allowance.

Start with your wall area

Use actual wall area, not the room’s floor area. Check coverage and coats on the paint you have chosen.

Area unit

How will you enter wall area?

Total wall area (m²)

Add width × height for each wall. Include openings here, then subtract them below.

Doors and windows to exclude (m²)

Optional. Leave blank for 0. Use the same area unit as the walls.

Coverage unit on the product label

Coverage for one coat (m² per litre)

No coverage figure is assumed. If the label gives a range, choose the rate appropriate to your surface; ask the manufacturer if unsure.

Number of coats

Enter the product’s required whole number of coats. Primer and different paint products need separate calculations.

Additional allowance (%) — optional

Your choice, not a recommendation. Blank means 0%. An allowance cannot guarantee there will be enough paint.

Your entries stay in this page, without being saved or sent to our servers. Use a decimal point (1.5), not a decimal comma or thousands separator.

Metric, US and Imperial

One area. Clear quantities.

Enter your areas, chosen coverage and coats to see the same paint estimate in litres, US liquid gallons and Imperial gallons.

Illustrative example40 m² × 2 ÷ 10 = 8 L

With a reader-selected 10% allowance: 8.8 L. The coverage and allowance are examples, not product recommendations.

Browser-only calculation. No analytics, account or saved entries.

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