This calculator turns project measurements into litres of paint based on area, number of coats and stated coverage. It is intended for early planning, quantity comparisons and checking a supplier estimate—not as a substitute for drawings or a professional takeoff. Keep every input in the same unit system and measure the actual project rather than relying on nominal dimensions.

How the calculation works

The calculation used here is wall area × coats ÷ coverage per litre × (1 + waste percentage ÷ 100). For 40 m², two coats, 10 m²/L coverage and 10% extra, the estimate is 8.8 L. Change one input at a time to see which assumption has the greatest effect. The displayed result is rounded for practical use, while the underlying calculation keeps the entered values. Always round purchase quantities in the direction that avoids a shortage.

Where this estimate is useful

It is particularly useful for interior walls, ceilings and other measured paintable surfaces. A quick estimate helps compare alternatives, prepare a shopping list and spot an unrealistic quotation before work begins. For several separate areas, calculate each section individually when their dimensions or specifications differ, then add the results. This avoids hiding important variation inside one average measurement.

What can change the result

Porous surfaces, major colour changes, application method and product-specific coverage can materially change consumption. Measure twice, confirm product dimensions on the manufacturer or supplier data sheet, and check whether materials are sold individually, by pack or only in fixed delivery quantities. Waste is a planning allowance rather than a universal constant: simple layouts usually need less, while complex cuts and fragile materials need more.