Paint Calculator
Estimate paint needed for walls and rooms. Free. No signup required.
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INSTANT · FREEAssumes identical walls. Coverage varies with surface texture, primer and paint. Converted dimensions use metric coverage (m²/L).
How to use this calculator
Estimate the amount of paint for matching walls. Subtract the area of doors and windows, choose the number of coats and use the coverage listed for your paint.
- Choose meters or feet for the wall dimensions and opening area.
- Enter a wall width and height, then the number of walls with those dimensions.
- Enter the combined area of doors and windows you will not paint.
- Enter the number of coats, coverage in square meters per liter per coat, and an extra allowance percentage.
- Read the estimated paint amount in liters and US gallons.
Calculation formulas
- Net area = wall width × wall height × matching walls − opening area
- Paint (liters) = net area in m² × coats ÷ coverage × (1 + extra allowance ÷ 100)
- US gallons = liters ÷ 3.78541
Four matching walls with two coats
Width: 5 m · Height: 2.5 m · Walls: 4 · Openings: 4 m² · Coats: 2 · Coverage: 10 m²/L · Extra: 10%
- Net wall area
- 46.00 m²
- Paint estimate
- 10.12 L
- Paint estimate
- 2.67 US gal
The four walls have 50 m² of area. Subtracting 4 m² of openings leaves 46 m². Two coats at 10 m²/L need 9.2 L; a 10% extra allowance brings the estimate to 10.12 L.
Useful to know
The walls in one calculation must share the entered width and height. Coverage depends on the paint and surface. Use the product coverage as a starting point and round your purchase up to the available can sizes.
Frequently asked questions
What coverage value should I use?
Use the coverage listed for your paint, in square meters per liter for one coat. If a range is given, a lower coverage value produces a larger paint estimate. Rough or porous surfaces may need more paint.
Can I enter dimensions in feet?
Yes. Choose Feet / ft² and enter wall lengths in feet and opening area in square feet. The calculator converts those inputs internally. The coverage field still uses m² per liter, and the results include both liters and US gallons.
What if the walls are different sizes?
Calculate each group of matching walls separately and add the paint estimates. You can also estimate a ceiling as one rectangular surface by entering its two dimensions.
Are primer and multiple paint colors included?
No. Calculate primer and each paint color separately, using the area, coats and coverage that apply to that product.