CalcPenguin

Paint Calculator

Enter the room size to see how many litres of paint, and how many gallon tins, you need for the walls and ceiling.

Your numbers are saved in this browser.
ft
ft
ft
sq ft
sq ft

Check the tin. Emulsions usually cover about 90 to 120 sq ft per litre per coat.

Paint needed

9.6 litres

Gallon tins (3.64 L)
3
Area to paint
480 sq ft

2 coats over 480 sq ft needs about 9.6 litres: 3 gallon tins of 3.64 litres.

How it's worked out

  1. Wall area2 × (14 + 12) × 10520 sq ft
  2. Minus doors and windows480 sq ft
  3. Paint480 × 2 coats ÷ 100 sq ft per litre9.6 L
  • A new or patched wall usually needs a primer coat first. Rough or porous walls drink more paint.

How paint is worked out

Litres = (wall area + ceiling − doors and windows) × coats ÷ coverage per litre

Wall area is the room's perimeter times the wall height: 2 × (length + width) × height.

Worked example

A 14 × 12 ft room with 10 ft walls has 520 sq ft of wall. Leaving out 40 sq ft of doors and windows gives 480 sq ft. Two coats at 100 sq ft a litre take 9.6 litres: three 3.64-litre tins.

Questions people ask

How much area does one litre of paint cover?

Most emulsions cover about 90 to 120 sq ft per litre for each coat on a smooth, primed wall. The tin gives the exact figure.

How big is a gallon of paint in Pakistan?

Paint sold as a “gallon” in Pakistan is usually 3.64 litres, a little smaller than a US gallon (3.785 L).

How many coats do I need?

Two coats is standard. A new or patched wall needs a primer first, and a strong colour change may need a third coat.

Formula and rules last checked 25 October 2026Written and tested by the CalcPenguin teamReport a problem