Paint coverage, coats and tin size are three separate inputs

A spreading rate such as 10 m²/L normally describes one coat under stated conditions. Two coats over the same wall require two passes over its area. Tin size affects the purchase count after the litres have been estimated.

A worked example

Item	Example or check
Net area	40 m²
Coats	2
Illustrative coverage	10 m²/L per coat
Paint before extra	8 L
With 10% extra	8.8 L

Check the assumptions

If the manufacturer gives a product-specific rate, enter that value instead of relying on the example. A rate given in square feet per gallon also needs the correct gallon: US and imperial gallons are not equal.

Compare two scenarios by changing only one input at a time. For example, lower coverage from 10 to 8 m²/L while keeping the area and coats fixed. The required volume rises from 8 to 10 L before extra. This shows the sensitivity to coverage without pretending to predict your surface.

Before using the estimate

Primer, finish and specialist coatings may require separate estimates. Do not combine different products into one coverage rate unless the supplier has given a valid basis.

Open the Paint Calculator and compare your measurements with the example.

Further reference: Publisher or manufacturer guidance. Product specifications can change; use the current label.