Hardware, machinery and home
Paint calculator
Enter the wall measurements, doors, windows and surface to find approximate litres and paint cans.
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Hardware, machinery and home
Availability and the suitable product will be confirmed by our team.
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Before placing an order
This estimate includes a 10% allowance. For prepared and primed surfaces, select the prepared option; exposed or very porous surfaces may require more paint. Actual absorption, colour and application tool can change the result.
Calculation guide
How to calculate paint needed for a room
Use this guide to take the right measurements and turn the result into a safer paint purchase.
Start by measuring the total length of every wall to be painted, then multiply it by the wall height. This gives the gross area. Deduct relevant openings afterwards: this calculator uses 1 m² per window and 1.5 m² per door. Small fittings are normally not deducted because cutting-in and touch-ups tend to offset their area.
Two coats are the usual reference for even coverage, especially when changing colour. Primer does not replace finish coats: it evens out absorption and improves adhesion. Choose whether the wall is prepared and primed or exposed and highly porous, since brick, concrete block and aerated concrete can use substantially more paint when they have not been sealed.
The result includes a 10% allowance and rounds litres up to avoid running short. Then select a can size to see the number of containers and likely surplus. Treat the result as a planning estimate: actual coverage changes with the product, colour, roller, texture and absorption. Send the calculation to Ferragut if the surface is damaged, damp, external or needs an intense colour.
Methodology and contents updated on 14 July 2026.
Frequently asked questions
Quick answers before buying
How many litres of paint do I need per m²?
A wall paint can typically cover around 8 to 12 m² per litre and coat on a prepared surface. The calculator adjusts this reference to the surface and adds a 10% allowance.
Should I deduct doors and windows?
Yes, when they are relevant openings. The calculator deducts 1 m² per window and 1.5 m² per door.
When should I use primer?
Use it on new, repaired, powdery, stained or highly absorbent walls. It evens out absorption and helps the finish coat cover uniformly.
What if I have exposed concrete block?
Choose exposed or very porous and concrete block. The result will be more conservative; assess a suitable primer or sealer before buying.
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