How it’s worked out
Coverage is how many square metres a litre covers in one coat, printed on the tin. Typical emulsion covers 10–12 m² per litre (350–400 ft² per US gallon) on smooth, sealed walls, and noticeably less on new plaster, rough or porous surfaces.
Walls = 2 × (width + length) × height − doors − windows Paint = area × coats ÷ coverage
Paint for two coats
Worked out by this calculator for 2.4 m walls with one door (1.8 m²) and one window (1.5 m²), at 11 m² per litre:
| Room | Walls | Paint | Tins |
|---|---|---|---|
| 3 × 3 m | 25.5 m² | 4.6 L | 1 × 5 L |
| 4 × 3.5 m | 32.7 m² | 5.9 L | 1 × 5 L + 1 × 1 L |
| 5 × 4 m | 39.9 m² | 7.3 L | 1 × 5 L + 1 × 2.5 L |
| 6 × 5 m | 49.5 m² | 9 L | 1 × 5 L + 4 × 1 L |
Tips
- Two coats is normal; a big colour change can need three.
- Seal new plaster with a thinned mist coat first, which soaks in and uses more paint.
- Buy enough from one batch for each wall: colours can vary slightly between batches.
How to read the result
- Paint needed: litres (or gallons) for the coats you chose.
- Tins: the mix of tin sizes with the least left over.
- Walls and openings: the area painted, so you can check it.
Common mistakes
- Forgetting the second coat.
- Using the tin’s best-case coverage on new plaster or rough walls, which drink more.
- Leaving the ceiling out when you’ll paint it too.
How to use it
- Type the room’s width, length and wall height.
- Type how many doors and windows to leave out, and their sizes if they’re unusual.
- Choose the coats and check the coverage against your tin, then read the litres (or gallons) and tins.
Questions
How much paint do I need for a 4 × 3.5 m room?
About 5.9 L for two coats on 2.4 m walls, with one door and one window left out.
How much does a litre of paint cover?
Typically 10–12 m² per coat on smooth walls; check the tin, as it varies by paint and surface.
Should I include the ceiling?
Turn on Paint the ceiling too to add it. Ceilings usually take a different paint, so it’s often worth working them out separately.
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Elsewhere on Yuzool
- Square feet to square metres in Figure
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