How Much Paint Do I Need? Litres for Every Room Size (UK)
A 4 × 3 m room with a 2.4 m ceiling needs 5.1 litres of emulsion for the walls (two coats, one door and one window) and 2.0 litres for the ceiling. The chart below covers other sizes, and shows how much the coverage figure on the tin changes the answer.
Litres for common room sizes
Ceiling height 2.4 m, one door (1.6 m²) and one window (1.5 m²) taken off, two coats at 12 m² per litre:
| Room | Paintable wall area | Walls (2 coats) | Ceiling (2 coats) | Walls + ceiling |
|---|---|---|---|---|
| 3 × 3 m | 25.7 m² | 4.3 L | 1.5 L | 5.8 L |
| 3.5 × 3 m | 28.1 m² | 4.7 L | 1.8 L | 6.4 L |
| 4 × 3 m | 30.5 m² | 5.1 L | 2.0 L | 7.1 L |
| 4 × 4 m | 35.3 m² | 5.9 L | 2.7 L | 8.5 L |
| 5 × 4 m | 40.1 m² | 6.7 L | 3.3 L | 10.0 L |
| 5 × 5 m | 44.9 m² | 7.5 L | 4.2 L | 11.7 L |
How the coverage on the tin changes the answer
For the 4 × 3 m room, walls only, two coats:
| Coverage | Litres for the walls |
|---|---|
| 10 m² per litre | 6.1 L |
| 12 m² per litre | 5.1 L |
| 13 m² per litre | 4.7 L |
| 14 m² per litre | 4.4 L |
The tin states how far a litre goes, so use that figure in the paint calculator rather than guessing. Rough walls, bare plaster and dark colours need more.
How the number of coats changes it
| Coats | Litres for the walls |
|---|---|
| 1 coat | 2.5 L |
| 2 coats | 5.1 L |
| 3 coats | 7.6 L |
Two coats is the standard. Going from a dark colour to a light one (or the other way) may take three, and a primer or tinted undercoat will help.
How to buy the right tins
- Round up to the tins you can buy. 5.1 litres is a 5 litre tin and a 1 litre tin, or a 5 litre and a 2.5 litre tin if you want some to spare.
- Buy all the paint for a room in one go, and mix the tins into one container, so the colour is the same on every wall.
- Keep a little for touching up, in a small, full, sealed pot: air in the tin makes paint skin over.
- Allow for extras that are not included: the skirting boards, doors and window frames (they use gloss or satin paint), and a mist coat if the plaster is new.
Before you start
- New plaster needs a mist coat: emulsion thinned with about 30% water (follow the tin), so that it soaks in and seals the surface. Then paint two full coats.
- Prepare the walls. Fill holes, sand them, wash greasy areas and let them dry, because paint will not hide poor preparation.
- Houses built before about 1960 can have lead-based paint. Test before sanding or scraping, and do not dry-sand old paint.
Frequently asked questions
How many litres of paint do I need for a 4m x 3m room?
5.1 litres for the walls with two coats, if the room is 2.4 m high with one door and one window, and 2.0 litres for the ceiling. That is 7.1 litres in all.
How much does a litre of emulsion cover?
About 12 m² per coat on smooth, previously painted walls, and as little as 10 m² on rough or bare plaster. The tin states its coverage, and cheaper paints often cover less than premium ones.
What size tins does paint come in?
Most emulsion is sold in 1 litre, 2.5 litre, 5 litre and 10 litre tins. Larger tins cost less per litre, so buy one big tin rather than several small ones when you can.
Do I need to paint the ceiling the same colour?
No. Use a white or pale contract matt on the ceiling, which hides flaws, and your chosen colour on the walls. You will need separate tins.
More guides
Tools & materials for this project
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Estimates only. Quantities depend on your materials, site and supplier. Confirm important numbers before you order, and check the Building Regulations and any planning rules for anything structural or close to a boundary.