Paint Calculator — Calculate Paint Quantity
Calculate how many litres of paint you need for walls, ceiling, or exterior. Accounts for doors and windows deduction.
By SwiftCalcTools Editorial Team · Formula verified
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How to Use Paint Calculator
- 1Enter the required values in the input fields above.
- 2Click the Calculate button or results update instantly as you type.
- 3View your results in the output panel below the inputs.
- 4Adjust any values to recalculate instantly.
Frequently Asked Questions
For an average 12×10 ft room with 9 ft ceilings: wall area ≈ 396 sq ft minus doors/windows ≈ 360 sq ft. At 120 sq ft/litre with 2 coats = 6 litres. Add 10% wastage = ~7 litres. Most manufacturers rate interior emulsion at 100–120 sq ft per litre per coat.
Emulsion/distemper: 120–140 sq ft/litre. Premium emulsion (like Asian Paints Royale): 100–110 sq ft/litre. Exterior weather coat: 80–100 sq ft/litre. Primer/sealer: 130–150 sq ft/litre. Always check the actual can for the manufacturer's stated coverage as it varies by brand and surface porosity.
Yes, typically a different type of paint is used — white or off-white ceiling paint at a higher sheen than walls. This calculator lets you include or exclude the ceiling. Many contractors price ceiling painting separately. For a standard 10×12 room, ceiling = 120 sq ft = about 1 extra litre per coat.
Paint wastage accounts for: drips and spills (2–3%), brush/roller absorption (2–3%), paint left in tray/container (1–2%), uneven surface absorption (2–3%), and miscalculation buffer (1–2%). For textured or rough surfaces, add 20–25% instead of 10%. Better to buy extra than run out mid-coat.