📊 Paint coverage by type (per coat)
Typical coverage of one litre of paint in a single coat. It varies with the surface and the brand — the calculator keeps every value editable:
| Paint type |
Coverage (m²/L per coat) |
Usual coats |
| Latex / emulsion | 10 | 2 |
| Enamel | 12 | 2 |
| Textured / rustic | 6 | 1–2 |
| Primer / sealer | 8 | 1 |
📐 How it is calculated
Walls = 2 × (length + width) × height. Paintable area = walls − (doors + windows) + the ceiling (if painted). Multiply by (1 + waste) for the adjusted area, then litres = adjusted area × coats ÷ coverage (m² per litre per coat). Cans = round the litres up to the can size. Primer, if used, is a single coat at its own coverage.
✍️ Worked example
Room 4 × 3 m, 2.5 m high, ceiling not painted, 1 door (1.8 m²), 2 windows (1.44 m² each), 5% waste, 2 coats, latex at 10 m²/L per coat, 4-litre cans. Walls = 2 × (4 + 3) × 2.5 = 35 m². Openings = 1 × 1.8 + 2 × 1.44 = 4.68 m². Paintable = 35 − 4.68 = 30.32 m². With 5% waste = 31.836 m². Litres = 31.836 × 2 ÷ 10 = 6.37 L → two 4-litre cans.
💡 Pro tips
- Dark or intense colours often need an extra coat over a light or white base — add one coat if you are covering a strong colour change.
- Spraying wastes more paint than a roller from overspray — add roughly 10–15% extra waste when you use a sprayer.
- Ceilings are usually painted with a dedicated flat ceiling paint, a separate product from wall paint — buy it separately if you paint the ceiling.
- New plaster, patched walls and porous surfaces drink paint — seal them with a primer coat first so the finish coats cover evenly and you use less top-coat.
🌍 Naming around the world
Paint = pintura = Wandfarbe / Farbe = 塗料・ペンキ = 페인트 · Coat = mano / capa = Anstrich · Coverage = rendimiento = Ergiebigkeit · Primer = imprimante / sellador = Grundierung · Latex / emulsion = látex = Dispersionsfarbe · Ceiling = cielo / techo = Decke.
❓ Frequently Asked Questions
How much paint do I need for a room?
Work out the wall area with 2 × (length + width) × height, subtract the doors and windows, add a small waste factor, then multiply by the number of coats and divide by the paint coverage (m² per litre per coat). A 4 × 3 m room 2.5 m high, minus one door and two windows, at 2 coats and 10 m²/L needs about 6.4 litres — two 4-litre cans.
What is paint coverage per litre?
Coverage is how many square metres one litre covers in a single coat. Smooth latex/emulsion is around 10 m²/L per coat, enamel about 12 m²/L, and textured or rustic paints roughly 6 m²/L. The label on your paint is the best source — the calculator keeps it editable.
Do I need primer, and how much?
Primer or a sealer is worth it on new plaster, patched walls, strong colour changes or porous surfaces. It is normally one coat with a higher coverage (around 8 m²/L). Turn on the primer option and the calculator adds the litres and cans for a single sealer coat separately from the finish paint.