Paint Calculator
Calculate exactly how many litres of paint you need. Add multiple rooms, choose your paint type, and see how many tins to buy.
Paint Settings
Rooms
Paint Required
Total Area
38.9 m²
Litres Needed
6.5L
Coverage Rate
12 m²/L
Tins to Buy (always round up)
3
× 2.5L tin
2
× 5L tin
1
× 10L tin
Coverage Guide
Emulsion (standard)
12 m²/L
Emulsion (premium)
15 m²/L
Gloss / Satin
14 m²/L
Masonry paint
8 m²/L
Primer / Undercoat
10 m²/L
How to Calculate How Much Paint You Need
The amount of paint required for a room depends on the total wall area, the number of coats, and the coverage rate of the specific paint you are using. Coverage rates in the UK typically range from 8 m² per litre for thick masonry paint to 15 m² per litre for premium emulsions. Most standard emulsions cover around 12 m² per litre, which is the figure used as the default in this calculator.
To calculate wall area, measure the perimeter of the room (length + width × 2) and multiply by the ceiling height. Then subtract the area of doors (approximately 1.85 m² each) and windows (approximately 1.2 m² each) to get the net paintable area. Most rooms require two coats for a solid, even finish — particularly when painting over a darker colour or bare plaster.
Always buy slightly more paint than the calculation suggests. Coverage rates are approximate, and factors such as porous surfaces, textured walls, or uneven application can increase consumption. A good rule of thumb is to add 10% to your calculated amount and round up to the nearest tin size. Keeping a small amount of leftover paint for touch-ups is also recommended.