Buying the wrong quantity of paint is a common and costly mistake. In 2026, knowing how to calculate paint needs accurately helps you budget better, reduce waste, and avoid mid-project shortages.
Simple Calculation Method
- Measure the total wall area (Length × Height of each wall).
- Subtract doors and windows.
- Divide by the coverage rate (most quality emulsions cover 9–12 m² per litre for two coats).
- Add 10–15% extra for wastage, touch-ups, and porous surfaces.
Example
A standard room of 4m × 3.5m with 2.8m height (minus one door and one window) typically needs about 6–8 litres for two full coats, depending on the surface.
Extra Tips
- New or porous walls absorb more paint
- Dark colours or dramatic colour changes may need an extra coat
- Always keep a small amount for future touch-ups
