Paint Calculator
Enter the wall dimensions and number of coats — get the paintable area and how many litres to buy.
How the estimate works
Wall area = total wall length × height. Each door subtracts 1.6 m² and each window 1.2 m² (typical sizes). That area is multiplied by the number of coats and divided by the paint's coverage — most emulsions cover 10–12 m² per litre; check the tin. The suggested purchase rounds up to the nearest half litre and adds 10% for touch-ups.
Frequently asked questions
What does "total wall length" mean?
Add up the width of every wall you're painting. For all four walls of a 4 m × 3 m room that's 4 + 3 + 4 + 3 = 14 m.
How many coats do I need?
Two is standard. Going light over dark, or painting fresh plaster, often takes three; a same-colour refresh may get away with one.
Does ceiling paint work the same way?
Yes — enter the ceiling's length as "wall length" and its width as "height" (area is just length × width), set doors and windows to 0.
Last updated: 2026-07-13