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TCalculator.

Paint Coverage Calculator

This free paint coverage calculator gives you an answer in a couple of seconds, and shows the full working underneath so you can check it rather than take it on trust. Change any value and the result updates immediately. Nothing is stored, nothing is sent anywhere, and there is no sign-up.

Enter your values

Check the tin — most interior acrylics are 14–16 m²/L

Paint needed

4.9 L

Wall area to paint
39.2 m²
Total area including coats
78.4 m²
Buy
2 × 4 L tins

How this is calculated

  1. 1

    Measure the perimeter

    perimeter = 2 × (length + width)

    perimeter = 2 × (5 + 4)

    = 18 m

  2. 2

    Multiply by wall height

    gross area = perimeter × height

    gross = 18 × 2.4

    = 43.2 m²

  3. 3

    Subtract doors and windows

    net = gross − openings

    net = 43.2 − 4

    = 39.2 m²

  4. 4

    Divide by coverage, times the number of coats

    litres = net × coats ÷ coverage

    litres = 39.2 × 2 ÷ 16

    = 4.9 L

  • Add roughly 10% for touch-ups. Bare plaster or a strong colour change usually needs an extra coat.

How to use this paint coverage calculator

  1. Fill in your values. Every field starts with a sensible default, so you can change one number at a time and watch what it does to the result.
  2. Read the result. The headline figure sits in the pink box, with supporting numbers listed below it.
  3. Check the working. The breakdown shows each formula and the same formula with your numbers substituted in, so you can follow the method or reproduce it by hand.