Cubestack

Paint Calculator

Free paint calculator — enter your room size, doors and windows to find the wall area and how many litres of paint you need for 1, 2 or 3 coats, with tin sizes to buy.

Paint type (coverage per coat)

Paint needed

7.2 L

2 coats over 387.3 sq ft

Wall area
440 sq ft
Minus doors & windows
−52.7 sq ft
Buy
2 × 4 L
Primer (1 coat)
2.6 L

Doors counted as 0.9 × 2.1 m and windows as 1.2 × 1.2 m. Includes 5% extra for touch-ups. Rough or new plaster can take 20–30% more.

What is the Paint Calculator?

Paint needed = (wall area − doors and windows) × coats ÷ coverage. Most interior emulsions cover about 10–12 m² per litre per coat, so a typical 12 × 10 ft room needs around 7 litres for two coats.

How to use it

  1. 1

    Enter the room size

    And count doors and windows.

  2. 2

    Choose coats and paint type

    Two coats is standard.

  3. 3

    Read the litres

    And the tins to buy.

Features

  • Room-based

    Length, width and height in feet or metres.

  • Deducts openings

    Doors and windows subtracted.

  • Coverage presets

    Emulsion, exterior, primer, enamel — or your tin's figure.

  • Tins to buy

    20, 10, 4 and 1 litre combinations.

Popular uses

  • Repainting a room

    Buy the right amount once.

  • Contractor quotes

    Check the estimate.

  • Budgeting

    Compare paint brands by cost per m².

Frequently asked questions

Do I need primer?

For new plaster, bare wood or a big colour change, yes — one coat.

Why do I need more than calculated?

Rough or absorbent walls take 20–30% more.

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