Paint Calculator
Estimate wall paint quantity based on room dimensions, doors, windows, coats, and paint coverage. Get can size recommendations.
✓ Runs in your browser · Updated 2026-03-31Enter values and click Estimate Paint Needed to see results
How to Calculate Paint Quantity
Estimating paint quantity requires knowing the wall area, subtracting doors and windows, and factoring in the number of coats and the paint's coverage rate.
Wall Area = 2 × (Length + Width) × Height (in metres, then convert to sq ft × 10.764)
Door Deduction = Doors × 21 sq ft (standard 7 × 3 ft door)
Window Deduction = Windows × 15 sq ft (standard 5 × 3 ft window)
Paintable Area = Wall Area − Deductions
Paint (litres) = (Paintable Area × Coats) ÷ Coverage per Litre
Understanding Paint Coverage
Most interior emulsion paints cover approximately 100–120 sq ft per litre per coat on smooth walls. Textured or rough surfaces may reduce coverage to 80–100 sq ft per litre. Always check the coverage mentioned on the paint can.
Types of Interior Paint
- Distemper: Budget-friendly, basic finish — covers ~100 sq ft/litre
- Emulsion: Water-based, washable, smooth finish — covers ~110 sq ft/litre
- Premium Emulsion: Better durability and sheen — covers ~120 sq ft/litre
- Enamel: Oil-based, high gloss, for doors/windows — covers ~100 sq ft/litre
Tips for Painting
Always apply a primer coat before painting for better adhesion and coverage. Buy 5–10% extra paint to account for wastage and touch-ups. Two coats generally provide the best finish and colour depth.
Related Calculators
- Area Converter — Convert between sq ft, sq m, and other units
- Length Converter — Convert metres, feet, inches
Frequently Asked Questions
How much area does 1 litre of paint cover?
Most interior wall paints cover 100-120 sq ft per litre per coat. Exterior paints cover 80-100 sq ft. Premium paints may cover 120-140 sq ft. Always check the manufacturer's specifications.