Calculate litres before choosing cans
Litres = net area × coats ÷ coverage per coat × 1.10
Use square metres for the area and square metres per litre for coverage. The 10% allowance is already included: do not add it to the input area as well. Whole-can purchases use your entered can size. Compare different available formats and prices in the paint comparison tool.
For finished area per can: required volume = net area ÷ finished area per can × can size × 1.10. Coats are already included and are not multiplied again. US coverage uses ft²/US gallon; 1 US gallon = 3.785411784 L.
Worked example: 40 m² and two coats
At 12 m²/L per coat, the calculation is 40 × 2 ÷ 12 × 1.10 = approximately 7.33 L. With the selected example can size of 10 L, one can buys 10 L. Change the size to match your product.
Measure walls and ceilings separately
For a rectangular room, multiply the perimeter by the wall height, then subtract the area of doors and windows. Add the ceiling only if you will paint it. A 4 × 3 m floor is 12 m², while its walls at 2.7 m high are 37.8 m² before openings. Floor area is not wall area.
Check what coverage means
Select per-coat coverage for m²/L or ft²/US gallon per coat. If the label states finished area per can for the complete coat cycle, select that mode and enter the finished area; coats will not be multiplied again. Surface texture, preparation and application affect the actual consumption. Primer is a separate product and is not included in this guide’s result.
More than one room
Use the multi-room link after calculating to continue in the English project calculator. You can add rooms and a ceiling, adjust product coverage and save a named project on your device. This page also keeps a separate draft and lets you download, print or share its measurements.