Paint Quantity Calculator
Estimate how many litres of paint you need from wall size, doors and windows, coats and your paint coverage.
- Paintable area (sq ft)
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- Litres to buy (rounded up)
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An estimate only. Surface texture and the paint you choose change the real coverage.
What is the Paint Quantity Calculator?
This calculator estimates how much paint a room needs. Enter the wall length and height in feet, the number of walls, the area of doors and windows to leave out, the coats, and the coverage per litre printed on your paint tin. It shows the paintable area and litres required.
How it works
Paintable area is length multiplied by height and by the number of walls, minus the door and window area. Litres needed are the paintable area multiplied by the coats and divided by the coverage in square feet per litre. The buying figure rounds up to a whole litre.
How to use it
- Enter the length and height of a wall in feet and the number of such walls.
- Enter the total door and window area to subtract.
- Enter the coverage per litre from your paint tin and the number of coats.
- Read the litres needed and the rounded figure to buy.
Paint Quantity Calculator — FAQ
Where do I find the coverage per litre?
It is printed on the tin or the maker's data sheet, usually as square feet per litre for one coat. This tool needs you to enter it.
Should I include the ceiling?
Not by default. To include it, treat it as an extra wall by adding its length multiplied by its width to the area.
Why buy slightly more paint than the result?
Rough walls absorb more paint and you may need touch-ups later. A small extra amount from the same batch helps colours match.