What this tool does
Works out how much paint you need from area, number of coats, and the product’s spreading rate, including a waste allowance, in litres.
How to use it
- Enter the area to paint in square metres, deducting windows and doors.
- Enter the number of coats.
- Enter the product’s stated spreading rate in m² per litre.
- Enter the waste allowance and run it.
Worked example
100 m², two coats, 10 m²/L, and 10% waste give 100 × 2 ÷ 10 × 1.1 = 22 L.
Calculation method
Required coating volume
area*coats/coverage*(1+waste/100)Frequently asked questions
- Where do I find the spreading rate?
- On the can or in the manufacturer’s data sheet. The default of 10 is illustrative; rough or absorbent surfaces consume more than the stated rate.
- The first coat uses more than the second.
- True — absorbent substrates drink the primer coat. This tool applies one rate to every coat, so raise the waste allowance for thirsty surfaces.
What this tool does not cover
Substrate absorption, application method (brush, roller, spray), and colour hiding power are not reflected. Run it separately for primer, mid, and top coats if they differ.