Paint Calculator
Calculate how much paint you need (litres or gallons) for walls and ceilings based on room size, number of coats, and openings.
Results
How to Calculate Paint
Multiply the room perimeter by ceiling height for total wall area. Subtract roughly 2 m² (21 sq ft) per door and 1.4 m² (15 sq ft) per window. Divide by your paint's coverage rate (typically 10-12 m² per litre, or 350 sq ft per US gallon) and multiply by number of coats.
Frequently Asked Questions
How much paint do I need for a room?
A typical 3.6 x 3.6 m (12 x 12 ft) room with 2.4 m (8 ft) ceilings has about 36 m² (384 sq ft) of wall area. After subtracting a door and two windows, you need roughly 7.5 litres (2 US gallons) for two coats at standard coverage (10 m²/litre or 350 sq ft/gallon).
How many coats of paint do I need?
Two coats is standard for a colour change. One coat may be enough if recoating the same colour over a well-primed surface. Use primer plus two coats over new plasterboard/drywall or dark colours.
How much does paint cost?
Interior latex paint ranges from $25-$50 per gallon (budget to mid-range) or $50-$80+ for premium brands. A typical room costs $50-$150 in paint. Primer adds $15-$30 per gallon if needed.
What is the coverage rate for paint?
Most interior paints cover 350-400 sq ft (32-37 m²) per gallon on smooth surfaces. Textured walls, bare drywall, or porous surfaces reduce coverage by 20-30%. Always check the manufacturer's label for specific coverage rates.
Should I buy extra paint?
Buy 10-15% extra for touch-ups and future repairs. Keep leftover paint in a sealed container at room temperature. It stays good for 2-5 years unopened and is invaluable for patching scuffs and marks.