Enter your room dimensions, surface type, and number of coats. Get the exact number of litres and tins to buy — no guesswork, no waste.
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Add each room separately to get a combined total. Tick the ceiling box to include it in the calculation.
Room 1
Coverage: 12 m²/L per coat. New surfaces need more paint as they absorb more.
Repaints typically need 2 coats. New plaster often needs 3 (1 sealer + 2 top coats).
Add each room with its length, width, and wall height. Tick the ceiling checkbox to include the ceiling area.
New plaster and raw timber absorb more paint than a previously painted surface. Select the right type for accurate results.
The calculator returns total litres, a suggested tin combination, and a rough cost estimate based on mid-range paint prices.
Coverage rates per coat for standard water-based interior paint.
| Surface | Coverage (m²/L) | Typical coats |
|---|---|---|
| Repaint — similar colour | 12–14 | 2 |
| Repaint — significant colour change | 10–12 | 3 |
| New plaster or GIB (+ sealer coat) | 7–9 | 3 |
| Raw / bare timber (+ primer) | 6–8 | 2–3 |
| Concrete or masonry | 5–8 | 2 |
Coverage varies by brand and application method. Check the label on your specific product.
A typical 4m × 5m room with 2.4m ceilings has about 43 m² of wall area. At 12 m²/L over 2 coats, you need around 7–8 litres for walls, plus about 4 litres for the ceiling. Always buy 10% extra for touch-ups.
Most interior paints cover 10–14 m² per litre per coat on a repainted surface. New plaster absorbs more and typically gives 7–9 m² per litre. Always check the label on your specific product.
The calculator uses the full wall area without deducting for doors and windows. For most rooms this works well — the extra paint accounts for waste, touch-ups, and spillage. Only deduct if you have an unusually large amount of glazing.
Repainting a similar colour: 2 coats. Large colour change: 3 coats. New plaster: sealer coat + 2 top coats. Raw timber: primer + 2 top coats.
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