ConverterHub

Paint Calculator

Find how much paint to buy for a job.

Result

8.00 L
2.11 gal

How it is calculated

The paint needed is the surface to cover, times the number of coats, divided by how much area one litre covers: litres = area × coats ÷ coverage. Area is in square metres, coverage is in m² per litre (the tin states it), and coats is the number of layers. If coverage is blank or zero the tool assumes 10 m² per litre, and if coats is blank it assumes 2. Area must be above zero. The US-gallon figure is litres × 0.264172. The result is exact, with no allowance for waste, texture or a first coat of primer, so buy a little extra.

Worked example

A wall area of 40 m², a paint that covers 10 m² per litre, two coats. Total area to paint: 40 × 2 = 80 m². Paint: 80 ÷ 10 = 8.00 L. In gallons: 8 × 0.264172 = 2.11 gal. Because paint is sold in fixed tin sizes, you would round up to the nearest tin.

Try this example →

Common mistakes

  • Measuring the full wall and forgetting to subtract windows and doors, or the opposite, painting a door but not adding it.
  • Using the manufacturer's coverage for a smooth, sealed surface on raw plaster or brick, which soaks up much more paint.
  • Entering the tin size as coverage. The coverage field is area per litre, not tin volume.
  • Forgetting the ceiling or counting only one wall of a room.
  • Treating gallons as UK gallons. The conversion factor here is for the US gallon.

About this calculator

This calculator estimates how much paint a job requires by working out the total surface area to be covered from wall dimensions, then dividing that by the coverage rate a typical can of paint provides, adjusted for the number of coats planned. Doors, windows, and other unpainted areas are usually subtracted from the total so the estimate isn't inflated.

Homeowners and DIY painters use it before a shopping trip to figure out how many cans or gallons to buy for a room or an entire house exterior, avoiding both an expensive over-purchase and an inconvenient mid-project run to the store. Contractors also use similar math when quoting a job to a client.

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