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Paint calculator

  

A door is taken as 21 sq ft and a window as 15 sq ft. One litre usually covers 90 to 120 sq ft a coat, so check the tin. About 5% extra is added for waste and touch-ups.

ft
ft
ft

Paint the ceiling too?

Coats

sq ft per litre per coat

Paint needed

9.1 litres

433 sq ft to paint, 2 coats. Buy 1 × 10 L. About ₹4,000 at your price.

Wall area
433 sq ft
Area in m²
40.2
Litres per coat
4.5

Estimating paint without wasting money

Painters usually work out paint from the wall area, and the calculation is easy to repeat yourself. Measure each wall, multiply length by height, and take off the doors and windows.

For a 14 × 12 ft room with 10 ft walls, the wall area is 2 × (14 + 12) × 10 = 520 sq ft. Two doors at 21 sq ft and three windows at 15 sq ft remove 87 sq ft, leaving 433 sq ft. Two coats at 100 sq ft per litre is 8.66 litres, and with 5% extra it is 9.1 litres. A single 10-litre can is enough.

Wall texture changes the answer. A rough or fresh plaster wall soaks up more. A drastic colour change, from deep red to white, may need an extra coat. If you do not know the coverage, read the tin, since the brand's figure is the one to trust.

Add the ceiling only if you are painting it. It is the same sum: length × width. In a 14 × 12 ft room that is 168 sq ft, which adds nearly 3.5 litres for two coats.

Sources

What this calculator does not account for

  • Wall texture and the number of colour changes.
  • Primer and putty.
  • Curved or sloped walls.

How this is calculated

Formula: Litres from wall area

litres =(walls − openings) × coats ÷ coverage × 1.05

What the symbols mean

  • walls2 × (length + width) × height.
  • openingsDoors at 21 sq ft and windows at 15 sq ft.
  • coverageSquare feet one litre covers in one coat, about 100.

Good to know

  • The 1.05 adds 5% for waste and touch-ups.
  • Add the ceiling's length × width if you are painting it.

Read the full methodologyFound an error? Contact us

Worked examples

Each example is worked out by the same code as the calculator above.

14 × 12 ft room, 10 ft walls, 2 doors, 3 windows, 2 coats at 100 sq ft per litre

433 sq ft of wall. About 9.1 litres. Buy one 10-litre can.

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Questions

How much area does 1 litre of paint cover?

Usually 90 to 120 sq ft per coat on a smooth wall. Rough walls and dark-to-light changes use more. The tin states it.

How many coats do I need?

Two for most walls. One coat of primer first on new plaster or a big colour change.

Do I paint behind furniture?

Not usually, but remove or cover it. The tool counts full walls.

Which can size should I buy?

Buying the exact litres is rarely possible, so the tool picks cans that cover the total. A small leftover tin is useful for touch-ups.