Estimate how much
paint you need.
Enter your room dimensions, pick the number of coats, and we'll calculate exactly how much paint to buy — with deductions for doors and windows. Metric and imperial supported.
Calculate paint in 3 steps.
Measure Your Room
Enter the length and width of the room, plus the wall height. These three measurements give us the total wall area.
Deduct Doors & Windows
Enter how many doors and windows you have. We subtract their average area so you only buy paint for the surfaces you'll actually cover.
Get Your Paint Quantity
Pick the number of coats and see exactly how much paint you need in litres or gallons — plus the number of cans to buy.
Frequently Asked Questions.
The general rule is that one litre of paint covers about 10–12 square metres (or one gallon covers about 350–400 square feet) per coat. Measure your walls, subtract doors and windows, multiply by the number of coats, then divide by the coverage rate.
Most interior walls need two coats for full coverage and durability. If you're painting over a dark colour with a light colour, or using a dramatically different colour, you may need three coats. A primer coat may also be needed.
Yes, subtracting doors and windows gives a more accurate estimate. A standard door is about 2 square metres (20 sq ft) and a standard window is about 1.5 square metres (15 sq ft). Our calculator lets you enter the exact count.
On average, one litre of interior emulsion paint covers about 10–12 square metres per coat. One US gallon covers roughly 350–400 square feet. Coverage varies by paint brand, finish, and surface texture.
If you want to paint the ceiling, toggle the ceiling option in the calculator. The ceiling area equals the floor area (length × width). We recommend a separate, flat finish paint for ceilings.
Yes, the paint calculator is 100% free with no signup, no downloads, and no hidden costs.