Paint calculator
A litre of emulsion covers about 12 m² per coat, so the walls of a 4 × 3.5 m bedroom need about 5.5 litres for two coats.
- 5 litre tins
- 1
- 2.5 litre tins
- 1
- Area to paint
- 32.9 m²
Walls of a 4 × 3.5 m room, 2.4 m high, 2 coats at 12 m² per litre.
For one colour of emulsion. Woodwork such as doors and skirting needs its own paint.
Paint for common room sizes
Walls only, 2.4 m high, one door and one window, two coats at 12 m² per litre.
| Room | Size | Wall area | Paint | Tins to buy |
|---|---|---|---|---|
| Box room | 2.5 × 2.5 m | 20.9 m² | 3.5 L | 1 × 5 L |
| Small bedroom | 3 × 3 m | 25.7 m² | 4.3 L | 1 × 5 L |
| Bathroom | 2.5 × 2 m | 18.5 m² | 3.1 L | 1 × 5 L |
| Double bedroom | 4 × 3.5 m | 32.9 m² | 5.5 L | 1 × 5 L + 1 × 2.5 L |
| Living room | 5 × 4 m | 40.1 m² | 6.7 L | 1 × 5 L + 1 × 2.5 L |
| Large open-plan room | 7 × 5 m | 54.5 m² | 9.1 L | 2 × 5 L |
How we calculate this
We add up the area of all four walls, take off doors and windows, and add the ceiling if you are painting it. Then we multiply by the number of coats and divide by how much one litre covers.
Tins: we use as many 5 litre tins as we can, then add a 2.5 litre tin if that covers the rest. Coverage defaults to 12 m² per litre. Tins often say up to 13, but bare plaster, textured walls and strong colours use more.
Questions people ask
How many coats of paint do I need?
Two coats is usual for walls. You may need a third when painting a light colour over a dark one. New plaster needs a thinned first coat (a mist coat), which uses extra paint.
How much does a litre of paint cover?
Most UK matt emulsions say 10 to 13 m² per litre on the tin. Real coverage is often a little lower, especially on bare plaster or rough walls, so check your tin and allow a bit extra.
Should I take off doors and windows?
Yes. We take off 1.6 m² for each door and 1.5 m² for each window. For a very large window or patio doors, measure it and add the area to the doors count instead.
Is it better to buy one big tin or two small ones?
Larger tins usually cost less per litre. If you have a little left over, keep it for touch-ups, sealed and stored somewhere frost-free.
Does this include woodwork?
No. Skirting boards, doors and window frames usually take a different paint, such as gloss or satinwood. A 750 ml tin is often enough for the woodwork in one room.
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