CostimexFree tool
Paint Quantity Calculator
Calculate exactly how much paint you need for a room — by area, number of coats and product coverage.
Most emulsions cover ~10–12 m²/L (350–400 ft²/gal). Check the tin for the exact rate.
Paint needed
7.31 L
≈ 1.93 gallons
Wall area
40.2 m² (per coat)
FAQ
Common questions
How much paint do I need per square metre?+
Most emulsions cover ~10–12 m² per litre per coat (350–400 ft²/gal). Textured walls, dark→light colour changes and porous new plaster all reduce coverage.
How many coats of paint should I apply?+
Two coats is the standard for new plaster, primer + 2 topcoats for bare wood and metal, and one coat is usually enough for a refresh of the same colour.
Does the calculator deduct doors and windows?+
Yes — enter the total opening area (m² or ft²) and it's subtracted from the gross wall area before applying coverage.
Litres vs gallons — which should I pick?+
UK and EU products are sold in litres; US products in gallons. Use the unit toggle to match your supplier. 1 US gallon ≈ 3.785 L.
Should I add a primer?+
Yes if you're painting new plaster, bare wood/metal, or covering a strong colour. Primer typically covers 8–10 m²/L. Add a separate coat in the 'Coats' input or run the calculator twice.
Need a professional estimate?
Our team delivers full quantity takeoffs and CSI-divided cost estimates in 24–48 hours.