Find the surface to be painted, divide by coverage per litre, then round up tins if needed.
Key formulas
Which faces?
Open boxes skip the top. Rooms may skip the floor. Read which surfaces receive paint.
Example
Area 48 m², coverage 12 m²/L → 4 L exactly. If coverage is 10 m²/L, you need 4.8 L → buy 5 L if only whole litres are sold.
Two coats
Double the area (or double the litres) when two coats are specified.
Worked example
Worked example
Problem. Wall area 48 m². One litre covers 12 m². How many litres for two coats?
Solution. One coat: 48/12 = 4 L. Two coats: 8 L.
Windows
Subtract window area if the question says they are not painted.
Review quiz
Wall 60 m², coverage 8 m²/L, two coats. Litres needed:
Practice questions
- Wall area 60 m², coverage 8 m²/L, two coats. Litres needed?
- Why round up tins rather than down?
Study notes
Is wastage included?
Only if the question adds a percentage for wastage.