Paint Calculator
Work out the gallons of paint and primer and the kilograms of filler your walls and ceilings need for a two-coat finish at the rate you actually specified.
Calculator
How the calculation works
Paintable area = net wall and ceiling area. A 3.78 litre gallon of emulsion covers roughly 30-35 m2 per coat on a properly prepared surface, so two coats need twice that, while primer is a single coat. Rough, porous or freshly plastered surfaces cut the spreading rate sharply.
Frequently asked questions
How much area does one gallon of paint cover?
30-35 m2 per coat on a smooth, well prepared surface. Textured or absorbent substrates can bring that down to 20-25 m2, which is where most paint overruns start.
Is primer really necessary?
Yes. It evens out absorption, holds the colour stable and cuts topcoat consumption. Skipping it costs more paint than it saves and shows up as patchy sheen.
How do I measure the paintable area of a room?
Wall perimeter x ceiling height, plus the floor area for the ceiling, minus doors and windows. As a rough check, painted area is often 3 to 3.5 times the floor area.
Does the calculator cover exterior paint?
The same arithmetic applies, but exterior and elastomeric coatings have their own spreading rates. Take the figure from the product data sheet and enter it as the coverage.
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This calculator is also available in Arabic: حاسبة الدهانات.