Paint Quantity Calculator

Work out paint quantity instantly with clear inputs, formula shown and shareable results.

About Paint Quantity Calculator

Paint quantity is net wall area times coats divided by coverage. Deduct about 1.8 square metres per door or window, and remember that stated coverage assumes a smooth sealed surface — bare plaster or textured walls can consume half again as much on the first coat.

Formula

Paint quantity

litres = (wall area - openings) x coats / coverage per litre

Worked example

With the default values below, Paint Quantity Calculator returns Paint required of 6.77. Change any input above and every figure here is recalculated in your browser.

Inputs used

Wall area to paint: 46 m²
Coats: 2 coats
Paint coverage: 12 m²/L
Doors and windows to deduct: 3 openings

Results

Paint required: 6.77 L
Net area to paint: 40.60 m²
2.5 L tins needed: 3 tins
Total area to cover: 81.20 m²

Step by step

1Values used
2Paint quantity
3Paint required= 6.77 L
4Net area to paint= 40.60 m²
52.5 L tins needed= 3 tins
6Total area to cover= 81.20 m²

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does the first coat use more?

Porous or unsealed surfaces absorb paint. A mist coat thinned with water on new plaster seals it and saves topcoat.

Is stated coverage reliable?

It is a best case on a smooth primed surface. Reduce it by 20-30% for textured, dark or previously unpainted walls.