Read the coverage figure
Coverage states an area per quantity of paint and must be interpreted using the product information. Enter coverage for one coat. Do not double the figure because you intend to apply two coats: the calculator handles coats separately.
For 32 m² of walls and two coats, the accumulated application area is 64 m². At 10 m² per litre per coat, the operation is 32 × 2 ÷ 10 = 6.4 L before adding any allowance.
Apply the allowance once
An allowance of 10% on 6.4 L adds 0.64 L, giving a target of 7.04 L. This percentage is a project choice, not a guarantee that the quantity will suit every texture, surface or change of colour.
If the product states a coverage range, compare several scenarios and keep the results. An estimate is not a promise: the substrate, application method and product requirements need to be checked separately before buying.
Round to whole tins
For 2.5 L tins, divide 7.04 by 2.5. You need three whole tins, providing 7.5 L. The 0.46 L difference comes from the pack size, in addition to the allowance already applied.
If you enter a price per tin, the cost covers three tins. It does not include primer, tools or delivery. To compare pack sizes, repeat the calculation with the actual volume and price of each option without mixing their figures.
- Distinguish coverage per coat from coverage for the complete job.
- Use the volume of the tin you intend to buy.
- Calculate primers and different paint products separately.
Frequently asked questions
Do extra coats need extra allowances?
Coats already multiply the base requirement. The allowance is applied afterwards; you do not need to add it again for every coat.
Can I combine different tin sizes?
This tool uses one pack size per calculation. For a combination, manually check that total litres cover the target and compare the combined price.