Solo Biz Soft Editorial Team Running out of paint halfway through a wall is annoying, and buying far too much wastes money. A quick calculation avoids both. Here is how to work out how much paint a room needs.
Step by step
- Measure the length, width and height of the room.
- Calculate the wall area: 2 × (length + width) × height.
- Subtract about 1.8 m² (20 sq ft) for each door and 1.2 m² (15 sq ft) for each window.
- Add the ceiling area (length × width) if you are painting it.
- Multiply by the number of coats.
- Divide by the coverage on the tin, for example 10 m² per litre.
Worked example
A room 5 m by 4 m with 2.5 m walls has 45 m² of wall. One door and two windows remove about 4.2 m², leaving 40.8 m². Two coats is 81.6 m². At 10 m² per litre, you need about 8.2 litres.
Tips
- Check the coverage on the tin, because it varies by brand and finish.
- Dark colours, bare plaster and rough surfaces need more paint.
- Buy all the paint for a room at the same time to keep the colour consistent.
- Add 5 to 10 percent for touch-ups.
Skip the arithmetic with our free paint calculator. For floors, use the tile calculator and the area calculator.
Frequently asked questions
How much paint do I need for a small room?
It depends on size and coats. Use the calculator with your measurements.
Do I include the ceiling?
Only if you are painting it, and often with a different paint.
How many coats do I need?
Two coats are common. Some colour changes need more.
More free tools: browse all our free calculators.
Estimates only. Follow the manufacturer’s instructions.