How Much Paint Do I Need?
Measure once, buy once, and never run out halfway up a wall.
The formula is simple: paintable area × number of coats ÷ coverage per litre. Our paints cover up to 14 m² per litre per coat, so a 2.5L tin of wall paint covers about 35 m² with one coat, or 17.5 m² with the two coats we recommend. Use the calculator below for a quick estimate, then read on for doors, windows, new plaster and woodwork.
At a glance
- Litres needed = paintable area (m²) × coats ÷ coverage (m² per litre).
- Our paints cover up to 14 m² per litre per coat. Plan for two coats.
- A 2.5L tin covers about 17.5 m² with two coats.
- Walls: add up height × width for each wall. Ceiling: length × width.
- Allow extra for new plaster, strong colour changes and rough or porous surfaces.
Paint calculator
Open the calculator, enter your room size and choose what you are painting. It measures the whole wall area (it does not subtract doors and windows), so its answer is a little generous, which is usually what you want.
How to work it out yourself
Measure each wall’s height and width and multiply them. For a simple rectangular room, the walls add up to 2 × (length + width) × height. Subtract any large doors and windows you have measured. Multiply by the number of coats, then divide by the coverage on the tin.
Worked example: a 4m × 3m room with 2.4m ceilings has 33.6 m² of wall. Two coats at 14 m² per litre is 4.8 litres, so two 2.5L tins. Take off a door and a window (say 3.5 m² together) and you need 4.3 litres: still two tins. The ceiling on its own is 12 m², or about 1.7 litres for two coats: one tin. Walls and ceiling together in the same colour come to about 6.5 litres: three tins.
Woodwork and radiators
Woodwork takes far less paint than walls. As a rough planning guide we use about 0.15 m² per metre of skirting, around 3.5 m² for a door (both faces and edges), 1 m² for a door frame and architrave, and 1.2 m² for a window frame, sill and reveal. A single-panel radiator is about 1.4 m², a double about 1.8 m² and a column radiator about 2.5 m².
Trim & Woodwork Paint and Radiator Paint come in 1L tins. At two coats, 1L covers about 7 m²: roughly one door, its frame and the skirting of a typical room. Add a tin for extra doors, windows or radiators.
When you will need more
New plaster is thirsty. Once it is fully dry, budget for a sealing mist coat before your finishing coats, following the product’s instructions. A big colour change, especially light over dark or dark over light, may need more than two coats. Textured, porous or patched walls also drink more paint than smooth ones.
Coverage figures are always "up to": rollers, technique and surface all play a part, so round up rather than down.
Sample it the way we would
Step 1
Paint your peel-and-sticks
Each £5.99 sample comes with three paintable peel-and-sticks. Give them two coats and let them dry fully.
Step 2
Stick them around the room
Put them on two or three walls, including the wall opposite the window, at eye level and lower down.
Step 3
Live with them for a day or two
Look in the morning, the afternoon and under your evening lamps. Move them around until you are sure.
Your questions, answered
How much does a 2.5L tin of paint cover?
Our paints cover up to 14 m² per litre per coat, so 2.5L covers about 35 m² with one coat, or 17.5 m² with two.
Is 5 litres of paint enough for a room?
Five litres covers about 35 m² at two coats, which is the walls of a typical 4m × 3m bedroom. Measure your own room rather than relying on "one room".
Do I subtract doors and windows?
In a manual calculation, yes, subtract anything large you have measured. Our calculator uses the whole wall area, so it gives a slightly generous answer.
Does new plaster need more paint?
Yes. Bare plaster is absorbent, so allow for a sealing mist coat on top of your two finishing coats.
Will two coats always be enough?
Usually, with our high-opacity paints, but strong colour changes can need a third. Sample first so you know how your colour covers.