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Paint litres and whole cans

Estimate paint volume and whole cans for one product. Calculate primer and topcoat separately when their coverage differs.

Start with your own numbers

Editable example

An example is filled in. Replace it with your own data to calculate.

Enter area, coats and coverage per liter separately, using this paint product's label.

Area to paint (square metres)Enter area to paint (square metres), for example 50. Use the displayed unit; replace the example with your own value.

Number of coatsEnter number of coats, for example 2. Use the displayed unit; replace the example with your own value.

Coverage per litre per coat (square metres)Enter coverage per litre per coat (square metres), for example 10. Use the displayed unit; replace the example with your own value.

Waste allowance (%)Enter waste allowance (%), for example 10. Use the displayed unit; replace the example with your own value.

Can size (litres)Enter can size (litres), for example 3. Use the displayed unit; replace the example with your own value.

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Example result

Minimum quantity of this paint to prepare

4cans

Calculate primer and topcoat separately. Cans round up; coverage is not identical across brands.

Estimated amount needed11 L

Volume purchased12 L

Estimated amount left1 L

Worked steps

50 m² × 2 coats ÷ 10 m²/L/coat × (1+10%).
Divide liters needed by can size and round up; calculate primer and topcoat separately.

Calculate one product at a time: primer and topcoat have different coverage, so calculate and save them separately. Deduct unpainted doors and windows from area first. Use the actual product's coverage per coat. Examples are not universal brand values or a contractor's quote.

Method and scope

Required litres equal area times coats divided by coverage, multiplied by (1 plus waste allowance). Round required litres divided by can size upward to buy whole cans.

Coverage must be specified per coat, not as a completed multi-coat system. Subtract unpainted openings from the measured area before entering it.

Use the actual product label and account for surface condition yourself. Example coverage is not universal across brands, and the result is not a contractor's quotation.

References:Sherwin-Williams: coverage and surface conditions

What this helps you do

Estimate paint volume and whole cans for one product. Calculate primer and topcoat separately when their coverage differs.

What to enter

Start with area to paint (square metres), then fill the other relevant fields in the units shown. The field hints explain the required format and examples.

How the calculation works

Required litres equal area times coats divided by coverage, multiplied by (1 plus waste allowance). Round required litres divided by can size upward to buy whole cans.

Worked example

Painting 30 square metres with two coats at 10 square metres per litre per coat uses 6 litres before waste. A 10% allowance gives 6.6 litres, requiring three 3-litre cans.

Understanding the answer