Wall Paint Coverage Calculator
Calculate exactly how many litres of paint you need for interior walls — any room size, any number of coats. Deducts doors and windows automatically. Get your order quantity in seconds.
🔨 Wall Paint Coverage Calculator
📐 How It Works
Wall paint quantity is the net wall area (perimeter × height minus openings) divided by the spreading rate, multiplied by the number of coats. Add 10% for roller waste and touch-ups. Always check the spreading rate on your specific paint tin.
📋 Worked Example
Bedroom 4m × 3.5m, 2.7m ceiling, 1 door, 2 windows, 2 coats at 12 m²/L: Perimeter = 15m. Gross = 40.5 m². Deductions = 4.6 m². Net = 35.9 m². Litres = 35.9 ÷ 12 × 2 = 5.98L. Order 6.6L.
❓ Frequently Asked Questions
A typical 4m × 3.5m bedroom with 2.7m ceilings needs approximately 5–7 litres for 2 coats on walls. This excludes the ceiling. Most paint is sold in 4L and 10L tins — buy one 4L plus one 10L for a standard bedroom repaint.
New plaster or bare surfaces: always prime first. Repainting same or similar colour: 2 coats topcoat usually sufficient. Major colour change: 1 coat primer + 2 topcoats. Stained walls: stain-blocking primer before topcoat.
The spreading rate (coverage) is printed on every paint tin — typically 10–14 m²/L for interior wall paint. This is the theoretical rate on a smooth surface. Real-world coverage is lower due to surface texture, roller nap and application. Always add 10% to your calculated quantity.
Ceiling paint: calculate room area (L × W) separately and add another 10–15% of that for 2 coats. Trim (skirtings, door frames, windows): typically 1–2 litres of enamel for a standard room. Calculate these separately from wall paint.