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Paint Coverage Calculator

How much paint do you actually need? Enter your room dimensions or total surface area, choose your paint type and number of coats — and get an exact litre figure.

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Enter your room dimensions or area to calculate how much paint you need.

Buy the right amount, first time. Dulux and Crown trade ranges are available in exact litre quantities — no more guessing which tin size to buy.

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How Paint Coverage Is Calculated

Most UK emulsion paints cover 10–16 m² per litre. The spread rate varies by paint type: matt emulsions are thicker and cover less, while gloss paints are thinner and spread further. Surface texture also matters — rough plaster or bare masonry absorbs more paint and will need more product.

For a standard room, the paintable wall area = perimeter × height, minus windows and doors (approximately 1.5–2 m² each). We add 10% to the final figure as a sensible contingency for edges, touch-ups and any variability in your spread rate.

Most quality emulsions only require 2 coats over a previously painted surface in a similar colour. Going from dark to light (or light to dark) may need 3 coats. Fresh plaster always needs a mist coat first (diluted 50/50 emulsion with water), then 2 full coats. Bare wood needs primer + undercoat + 2 gloss coats. One coat coverage claims are generally only accurate over the same colour.
Yes — always buy at least one pot more than your exact calculation. Paint batches can vary slightly in colour (dye lot variation), and touch-ups months later may not perfectly match if you've run out. Keep the leftover sealed in the original tin. Write the room name and date on the lid with a marker. Leftover paint stored correctly lasts 2–5 years.
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