Work out how much paint a room needs from its dimensions, coats, and openings.
—m² of wall (after openings)
—litres needed
—estimated cost
How it works
Wall area is the room's perimeter times wall height, minus a fixed area per door (1.6 m² / 18 sq ft) and per window (1.5 m² / 15 sq ft) since those obviously don't get painted; that net area is multiplied by your number of coats and divided by your coverage rate to get the litres or gallons needed.
FAQ
Why does switching units change my numbers slightly?
Switching between metric and imperial converts your existing width, length, and height values with a fixed 3.28084 conversion factor and rounds to 2 decimal places, so small rounding differences can appear compared to entering the imperial numbers directly.
Does it account for ceilings or trim?
No - it only calculates wall area from the four walls' perimeter and height; ceilings, trim, and door or window frames you plan to paint separately aren't included.
Free, unlimited, no account. If this saved you a paid tool, a small thanks is appreciated.