How much paint do I need?

Multiply your wall area by the number of coats, then divide by the coverage of the paint, usually around 10 square metres per litre. Most walls need two coats, and bare or dark surfaces may need more. The calculator turns that into litres and cans.

How do I measure wall area?

Add up the length of all the walls and multiply by the height. You can subtract large windows and doors, roughly 1.5 to 2 square metres each, if you want a tighter estimate. For a quick result, enter the total wall area you measured.

How many coats of paint?

Two coats is standard for a good finish over an existing painted surface. New plasterboard usually needs a sealer or undercoat first, and strong colour changes can need an extra coat. Set the number of coats to match your job.

Paint Calculator

This calculator works out how much paint you need for a painting job, so you buy the right amount instead of guessing and ending up short or with cans of leftover paint. You enter three figures: the total wall area in square metres, the number of coats you plan to apply, and the paint's coverage rate, usually around 10 square metres per litre for a typical wall paint, though this varies by brand and surface. From these the calculator returns the total litres of paint required, then converts that into a practical shopping list showing how many 10 litre cans and how many 4 litre cans you would need to cover that amount. If you do not already know your wall area, work it out by adding the length of each wall and multiplying by the ceiling height, and subtract large windows and doors if you want a tighter figure. Two coats is standard for most repaints, but bare plasterboard, colour changes, or dark surfaces often soak up more paint and may need an extra coat. Because coverage rates differ between paint brands and finishes, and porous or textured surfaces use more product than a smooth painted wall, treat the litres and can counts as a guide. Buy a little extra to allow for touch-ups, and check the tin's stated coverage against what you have entered here.

Calculate.co.nz is proud to be partnered with Health Based Building, a leader in sustainable and health-conscious building innovation. With over a century of experience, they develop high-performance systems like Foreverbreathe Specification, Magnum Board, and Foreverbreathe Paints to support energy-efficient, non-toxic living environments. Their commitment to healthier homes aligns with our belief that informed choices lead to better outcomes for Kiwi households.

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Wall area (m²)

Coats

Coverage (m² per litre)

0 L

paint needed

10 litre cans0

4 litre cans0

Buy a little extra for touch-ups. Bare or dark surfaces may need an extra coat.

How it works

The paint needed is the wall area times the number of coats, divided by the coverage. Coverage is usually about 10 square metres per litre on a smooth painted wall, but rough or porous surfaces soak up more, so the litres go up.

Worked example

For 60 square metres of wall at two coats and 10 square metres per litre, you need 60 times 2 divided by 10, which is 12 litres. That is two 10 litre cans, or you could buy one 10 litre and one 4 litre to have a little spare.

Related calculators

Square Metre Calculator: work out an area.
Wallpaper Calculator: rolls of wallpaper.
Tile Calculator: tiles for a surface.
Plasterboard Calculator: sheets for a room.

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