Paint calculator
Count how much paint and primer the walls and the ceiling of a room need. Windows and doors are taken out of the area, the number of coats is counted, and the result is rounded up to whole cans of the sizes sold in your region.
You need
3 cans of 2.5 l
5.7 l needed
- Primer
- 1 can of 5 l3.4 l needed
- Coverage
- 12 m²/l per coat
- Walls without windows and doors2 × (4.00 + 3.00) × 2.70 − 1 × 1.40 × 1.50 − 1 × 0.80 × 2.00 = 34.10 m²
- Area × coats34.10 × 2 = 68.20 m²
- Paint, 12 m²/l68.20 ÷ 12 = 5.68 l
- Cans of 2.5 l, rounded up5.68 ÷ 2.5 → 3 cans
- Primer: Area × coats34.10 × 1 = 34.10 m²
- Primer: Paint, 10 m²/l34.10 ÷ 10 = 3.41 l
- Primer: Cans of 5 l, rounded up3.41 ÷ 5 → 1 can
Consumption is the average from the «United Kingdom, Ireland, Australia and New Zealand» preset. Check it against your manufacturer's pack.
The calculator gives an estimate by the usual norms. Consumption depends on the product and the surface: check the manufacturer’s data before you buy.
How it’s calculated
- 1
Wall area = perimeter × height, minus windows and doors. Ceiling area = length × width.
- 2
Area to cover = area × number of coats.
- 3
Litres = area to cover ÷ coverage of one litre (m² per litre, from the can).
- 4
Cans = litres ÷ can size, rounded up.
- 5
Primer goes on in one coat and has its own coverage, usually higher than paint.
Worked example
The walls of a 4 × 3 m room, 2.7 m high, with one window and one door, two coats:
The input
- What we paint
- Walls
- Length, m
- 4
- Width, m
- 3
- Height, m
- 2.7
- Windows
- 1
- Doors
- 1
- Coats
- 2
- Can, l
- 2.5 l
- Primer first
- ✓
- Primer: Can, l
- 5 l
The result
3 cans of 2.5 l
5.7 l needed
- Primer: 1 can of 5 l
- Coverage: 12 m²/l per coat
The calculation
- Walls without windows and doors2 × (4.00 + 3.00) × 2.70 − 1 × 1.40 × 1.50 − 1 × 0.80 × 2.00 = 34.10 m²
- Area × coats34.10 × 2 = 68.20 m²
- Paint, 12 m²/l68.20 ÷ 12 = 5.68 l
- Cans of 2.5 l, rounded up5.68 ÷ 2.5 → 3 cans
- Primer: Area × coats34.10 × 1 = 34.10 m²
- Primer: Paint, 10 m²/l34.10 ÷ 10 = 3.41 l
- Primer: Cans of 5 l, rounded up3.41 ÷ 5 → 1 can
How much paint do I need for a room?
A 4 × 3 m room with 2.7 m ceilings has 37.8 m² of walls; without a 1.4 × 1.5 m window and a 0.8 × 2.0 m door it is 34.1 m². Two coats cover 68.2 m². At 7 m² per litre that is 9.7 litres, at 10 m² per litre 6.8 litres — the coverage on the can decides.
How many coats of paint?
Two coats are the norm for walls and ceilings: the first one evens out the surface, the second gives the colour. A change from dark to light, a fresh plaster or a bright colour may need a third. One coat is enough only when refreshing the same colour.
Do I need primer?
On new plaster, putty and drywall, yes: primer evens out the absorption, so paint goes on evenly and less of it is used. It is applied in one coat; a litre usually covers more than a litre of paint.
Questions
What does the coverage on the can mean?
It is how many square metres one litre covers in one coat on a smooth, primed surface. Rough or porous walls take more — that is why the calculator lets you choose the region whose cans and norms you buy.
Are windows and doors subtracted?
Yes. Each window and door is taken out of the wall area at its usual size; if you know the exact wall area, type it in instead.
Why buy a little more paint?
Paint of one batch has one shade. Buying it all at once, with some left for touch-ups, avoids a visible difference on the wall later.
The same calculator in the Kvadrino app
Kvadrino for Android works offline: enter the room once and get tiles, paint, flooring and an estimate for the client. The app is in closed testing — write to us and we will add you as a tester.
Coming soon to Google Play