Paint Calculator
Paint Calculator — runs in your browser. Inputs are not stored.
Paint cans needed
Enter values, then press Calculate.
How to use
- Enter the wall area (㎡) to paint. Subtract doors and windows first. The default example is 40.
- Enter the product label’s coverage (㎡/can). The default is 10. For litre cans, match area per can.
- Enter coats. The default is 2 (primer + topcoat, or two coats).
- Press Calculate to see the rounded-up number of cans. The formula is ceil(area × coats ÷ coverage).
- If you need a margin, enter a slightly larger area or buy one extra can. Follow the product’s stated coverage.
Key concepts
The paint calculator estimates how many cans you need from wall area, coverage per can, and number of coats, rounding up. Absorption, texture, and colour changes (light over dark) reduce coverage. Subtract doors and windows from the area first.
Add or omit ceilings and skirting via the area input. Calculation is local. Rough walls and colour reversal can increase real usage. Litre cans work if ㎡ per can is correct. High-absorption walls may need extra cans. Build in margin by entering a larger area.
Example
Wall 40 ㎡, 10 ㎡ per can, 2 coats: 40 × 2 ÷ 10 = 8 cans. Subtracting windows to 32 ㎡: 32 × 2 ÷ 10 = 6.4 → 7 cans after rounding up. Coverage 12 ㎡/can with the same 40 ㎡ and 2 coats rounds up to 7 cans. 25 ㎡ ceiling + walls, 8 ㎡/can, 2 coats: 25 × 2 ÷ 8 = 6.25 → 7 cans. Subtracting 3 ㎡ of windows reduces cans. 12 ㎡, 9 ㎡/can, 3 coats: 12 × 3 ÷ 9 = 4 cans. One coat drops that to 2 cans.
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Frequently asked questions
What should I do about doors and windows in the paint area?
Subtract them from the area first. This screen only multiplies the area you enter. Leaving window area in wastes cans.
Is the paint calculation sent to a server?
No. Calculation is local.
How much extra paint should I buy?
If needed, enter a slightly larger area. There is no automatic waste factor.
Do litre cans work too?
Match coverage in ㎡/can. Convert litres to cans and use the label’s ㎡/can. A 4 L can uses the label’s ㎡/can as-is.
Is the can count accurate?
It is for reference when you follow the product’s stated coverage. Roller loss can use more than the label.
Should I add the ceiling to wall area?
If you paint the ceiling, add width × length to the area. For walls only, enter the wall total. Adding ceiling area increases the can count.
Last reviewed: 2026-09-04