Step 1: Measure each room
For each room, measure the perimeter (the total length of all walls) and the ceiling height. Multiply them to get the wall area. Measure the length and width of the floor to get the ceiling area. Write these down room by room.
Our guide on how much paint you need for a room explains this in more detail.
Step 2: Check coverage
Look at the coverage on the tin – typically around 10–14 m² per litre for interior emulsion on smooth, previously painted walls. Divide the area by the coverage, then multiply by the number of coats.
Example: a 3-bedroom house
Here's an estimate for a typical three-bedroom semi with 2.4m ceilings, two coats throughout:
| Area | Approx. area | Paint needed |
|---|---|---|
| Walls (all rooms, hall, stairs) | 300 – 350 m² | 50 – 60 litres |
| Ceilings | 70 – 90 m² | 12 – 16 litres |
| Woodwork (doors, frames, skirting) | – | 5 – 8 litres |
| Exterior masonry (if rendered) | 120 – 180 m² | 40 – 60 litres |
Indicative paint quantities for a 3-bed semi (two coats)
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Allow for extras
Add 10–15% for wastage, touch-ups and the paint left in rollers and trays. You'll need more if:
- You're changing colour significantly
- Walls are new plaster or very porous
- Surfaces are rough or textured
- You're using strong or dark colours
Costs
Trade emulsion typically costs £3–£8 per litre, while premium and designer paints can cost £10–£20 or more. For a whole three-bed house interior, paint might cost £300–£900 depending on quality. Exterior masonry paint for a semi might cost £200–£500.
If you're hiring a decorator, they'll usually work out quantities and include paint in the price. See our guide to painting a 3-bed semi, and get quotes from local painters and decorators.
