Paint calculator
Enter the room size, doors, windows and number of coats to see how many litres of paint you need for the walls and ceiling, and which tins to buy.
The room
About 1.9 m² each
About 1.5 m² each
Check the tin. Emulsion is often 10 to 14.
Paint needed
How much paint do you need?
The calculator works out the wall area as the perimeter of the room times the wall height, then takes off about 1.9 m² for each door and 1.5 m² for each window. The ceiling area is the length times the width.
It then multiplies the area by the number of coats, divides by the coverage on the tin and adds 10% for waste, cutting in and touch-ups. Finally it suggests a mix of 5 litre and 2.5 litre tins.
Tips for accurate quotes
- Check the coverage on the tin. Trade emulsions vary, and rough or porous surfaces use more paint.
- Allow for a mist coat on new plaster, which usually needs thinned paint and an extra coat.
- Strong colour changes may need a third coat, especially going from dark to light.
- Woodwork is separate. Skirting, doors and frames use gloss or satinwood, priced per room.
Decorators using Cuppaflow get a paint calculator inside every quote, alongside good, better, best options by finish. See how it works for painters and decorators.
Questions and answers
How much does a litre of paint cover?
Many emulsions cover about 10 to 14 square metres per litre per coat on smooth surfaces. Always check the tin.
Do I need two coats?
Usually, yes. Two coats give an even finish, and new plaster or big colour changes may need more.
How do I work out wall area?
Add up the lengths of all walls, multiply by the height, then take off doors and windows.
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