How much paint for a ceiling?
2.7 litres a ceiling 4 × 4 m · 2 coats
A ceiling 4 × 4 m (16 m²) needs 2.5 litres of emulsion for 2 coats, 2.7 litres with 10% spare: buy 1 × 5 l. Without the spare, 1 × 2.5 l just covers it, with nothing left for a second pass over a patchy corner.
Ceilings punish thin coats. The light from the window rakes across them and shows every missed strip, so the second coat is not optional and running short halfway is the worst outcome. That is why the sum rounds up to the larger tin.
Some paints sold for ceilings cover less than wall emulsion, and a ceiling stained by damp or smoke needs a stain block first. Check the tin for its own coverage figure.
Worked out for A flat ceiling 4 × 4 m (13 ft 1 in × 13 ft 1 in), with 2 coats of emulsion that covers 13 m² a litre. Change the numbers
The working
- Ceiling: 4 m × 4 m = 16 m²
- Area to paint: 16 m²
- 16 m² × 2 coats ÷ 13 m² per litre = 2.5 l
- Plus 10% spare = 2.7 l
- Tins: 1 × 5 l = 5 l
Some ceiling paints cover less per litre than wall paint: check the tin.
The rules, and their sources
Emulsion coverage per litre
Dulux says its Walls & Ceilings matt and silk emulsions cover up to 13 m² per litre on average, per coat. B&Q's and Homebase's own calculators assume 10 m² per litre.
An industry guideline Sources: B&Q, Dulux Walls & Ceilings matt emulsion 2.5 l (checked 31 October 2026); B&Q, Dulux Walls & Ceilings matt emulsion 5 l (checked 31 October 2026); Screwfix, Dulux Pure Brilliant White silk emulsion 2.5 l (checked 31 October 2026); B&Q, Wall painting calculator (checked 31 October 2026); Homebase, Paint calculator (checked 31 October 2026).
Coats of emulsion
Two coats of emulsion is the usual advice for walls and ceilings; a strong colour change can need a third.
An industry guideline Sources: Homebase, Paint calculator (checked 31 October 2026); Dulux UK, How much paint do you need? (checked 31 October 2026).
Spare paint
B&Q and Homebase advise buying about 10% more paint than the area needs, for spills, mistakes and touch-ups.
An industry guideline Sources: B&Q, Wall painting calculator (checked 31 October 2026); Homebase, Paint calculator (checked 31 October 2026).
UK emulsion tin sizes
Emulsion comes in 2.5 l and 5 l tins (some colours in 1 l). At B&Q a 5 l tin costs less per litre: £36 (£7.20/l) against £25 (£10/l) for 2.5 l of Dulux Walls & Ceilings matt.
Shop sizes Sources: B&Q, Dulux Walls & Ceilings matt 2.5 l (checked 31 October 2026); B&Q, Dulux Walls & Ceilings matt 5 l (checked 31 October 2026); Dulux UK, How much paint do you need? (checked 31 October 2026).
Other ceilings
A ceiling's area is the floor's, so the sum is short: length times width, times the coats, divided by the coverage.
| Ceiling | Paint, with spare | Tins to buy |
|---|---|---|
| 3 × 3 m | 1.5 litres | 1 × 2.5 l |
| 4 × 3 m | 2 litres | 1 × 2.5 l |
| 4 × 4 m this page | 2.7 litres | 1 × 5 l |
| 5 × 4 m | 3.4 litres | 1 × 5 l |
| 6 × 5 m | 5.1 litres | 1 × 5 l + 1 × 2.5 l |
Change the numbers
Your sizes will differ. The paint calculator opens with these numbers filled in: change any of them and the answer, the working and the drawing follow.
Editorial notes
Worked out by the Snuug team on 12 November 2026 with the same code as the paint calculator, so the two cannot disagree. Every rule cites its source, with the date we last checked it. A rule designers use is a convention, not a study.
Other sources the calculator draws on:
- Howarth Timber (Green, 14 Sep 2026), UK door sizes, checked 31 October 2026