How many litres of paint do I need for a room?

For a standard 12×10 ft (3.7×3 m) room with 8 ft (2.4 m) ceilings, you need approximately 4–5 litres for two coats of wall paint. UK paint coverage is typically stated at 10–12 m²/litre; US coverage is quoted at 350–400 ft²/gallon. Always subtract door and window areas and add 10% extra.

What is the difference between US gallons and UK coverage rates?

US paint is sold in gallons (3.785 litres) and typically covers 350–400 ft² (32–37 m²) per gallon per coat. UK and Australian paint is sold in litres and covers approximately 10–12 m² per litre per coat. The effective coverage per volume is similar — about 10 m²/L or 400 ft²/gallon.

How many coats of paint do I need?

Two coats are standard for most walls. One coat may suffice if painting a similar colour over a well-prepared surface. Three coats are needed when painting a dark colour over a light one (or vice versa), using primer as the first coat, or covering a new drywalled surface. In humid climates (AU, SE Asia), three coats improve moisture resistance.

Paint Calculator — How Many Litres or Gallons to Paint a Room

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Calculate exactly how much paint to buy. Covers any number of coats and automatically deducts doors and windows. Shows results in both litres (UK/AU) and US gallons.

Quick Answer

Litres needed = Wall area (m²) × coats ÷ 10. Gallons = Wall area (ft²) × coats ÷ 400. Add 10% for touching up.

Room Length (ft)

Room Width (ft)

Ceiling Height (ft)

Number of Doors

Number of Windows

Number of Coats

Region	Coverage Rate	Can Sizes	Notes
🇺🇸 United States	350–400 ft²/gallon	1 qt, 1 gal, 5 gal	VOC limits vary by state (CA strictest)
🇬🇧 United Kingdom	10–12 m²/litre	1L, 2.5L, 5L, 10L	BS 3900 testing standards
🇦🇺 Australia	10–12 m²/litre	1L, 4L, 10L, 15L	AS/NZS 1580 standards
🇨🇦 Canada	~11 m²/litre	1L, 3.78L (1 gal)	VOC limits follow US EPA rules
🇩🇪 Germany	~10 m²/litre	0.75L, 2.5L, 5L	CE marking required post-2023

Frequently Asked Questions

How many litres of paint for a room?

For a typical 12×10 ft room (2 coats): ~4–5 litres, or about 1.25 gallons. Coverage depends heavily on surface porosity — new plaster absorbs far more paint than a previously painted surface. Dulux and Crown (UK) quote 10–12 m²/L on smooth surfaces, but new bare plaster may only achieve 6–8 m²/L on the first coat.

What is the difference between US and UK paint coverage?

US paint coverage is stated as ft² per gallon (typically 350–400 ft²/gal). UK coverage is stated as m² per litre (typically 10–12 m²/L). These are equivalent on a per-volume basis: 400 ft²/gal ≈ 10 m²/L. The real difference is can sizes: US paint comes in 1 gallon (3.785L) cans; UK cans are typically 2.5L, 5L, or 10L.

Do I need a primer coat?

Primer is needed for: new drywall (US) or new plaster (UK/AU), bare wood, highly porous masonry, and when dramatically changing colours. UK trade painters typically prime new plaster with a mist coat (heavily diluted emulsion paint). In Australia, sealer-primer is commonly used on new surfaces before topcoats.

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