Paint Calculator

Measure each wall’s width and height, multiply them, and add the walls together. For a rectangular room it’s (2 × length + 2 × width) × ceiling height. Our area calculator handles odd shapes if a wall isn’t a simple rectangle.

Yes, if they add up to much. A single door and window are roughly 3–4 m² combined; on a small room that’s a noticeable saving. Enter their total in the openings field and the tool removes them before calculating.

Check the tin — most walls emulsions state 10–12 m² per litre per coat. Textured, porous or dark-to-light surfaces cover less, so drop to 6–8 m²/L if in doubt. It’s the single biggest factor in the result.

Two is standard for good coverage over a similar shade. Painting light over dark, or covering a strong colour, often needs three. Fresh plaster wants a thinned mist coat first, then two topcoats.

Only if you add the ceiling area to the wall area. Ceilings are usually painted with a different (matt) paint, so many people calculate them separately using the room’s floor area as the ceiling area.

Tins come in fixed sizes (0.75, 2.5, 5, 10 L). Always round the litres up to the next combination of tins, and keep a little extra for touch-ups — paint from the same batch matches best.

It changes coverage, not the formula. Primers and undercoats often cover less than topcoats; gloss and specialist masonry paints vary widely. Use the coverage printed on each specific product.

No. The calculation runs entirely in your browser and nothing you type is sent to a server or to analytics.