Paint Calculator

What it is for

The paint calculator tells you how many liters and cans to buy to paint a room's walls, based on wall size, number of coats and can size. It suits DIY painters and people hiring a painter who want to avoid both running short and overspending on leftovers.

How it works

You enter the sum of the wall lengths (the perimeter to paint), the height, the number of coats and the can size in liters. Area is length × height. Liters equal area × coats ÷ 6, because the tool assumes 1 liter covers 6 m² per coat. Cans are liters divided by can size, always rounded up. To paint just one wall, enter only that wall's length.

Worked example

Walls totaling 20 m in length, 2.5 m high, 2 coats, 3.6 L cans. Area: 20 × 2.5 = 50 m². Liters: 50 × 2 ÷ 6 = 16.67 L. Cans: 16.67 ÷ 3.6 = 4.63, rounded up to 5 cans. About 1.3 L remains for future touch-ups.

Limits and caveats

The coverage of 6 m² per liter per coat is the tool's average; real coverage varies with brand, texture and color. The calculation does not subtract doors and windows or include the ceiling. Check the coverage stated on the can.

Frequently asked questions

How much paint do I need for a wall?

Work out the area (length × height), multiply by the number of coats and divide by the paint's coverage. Here coverage is taken as 6 m² per liter per coat. Always confirm the manufacturer's coverage on the label.

Do I need to subtract doors and windows?

This tool does not subtract openings, so the result tends to be slightly generous, which helps leave some for touch-ups. For more precision, remove the area of doors and windows from the total length you enter.

Why are cans rounded up?

Because you cannot buy a fraction of a can. If the math gives 4.63, you need 5 cans to cover everything. Having extra is usually better than running short, since different batches can differ slightly in shade.