How to Calculate Paint Coverage
What is Paint Coverage?
A paint coverage calculator estimates how many litres of paint are needed to cover a room's walls and ceiling. Standard paint covers approximately 10–12 m² per litre, depending on surface texture and paint quality.
Formula
gallons_needed = (area_sqft / coverage_sqft_per_gallon) × coats
- area
- Area (sq ft) — Wall/surface area to paint
- cov
- Coverage per gallon (sq ft/gal) — Typical: 300–400 sq ft/gal
- coats
- Number of coats (coats) — Usually 2; dark→light may need 3
- gallons
- Paint needed (gallons) — Total paint required
Step-by-Step Guide
- 1Wall area = 2 × (length + width) × height
- 2Ceiling area = length × width
- 3Total area = (walls + ceiling) × number of coats
- 4Litres needed = total area ÷ 10 (coverage rate)
- 5Deduct ~1.5 m² per door and ~1 m² per window
Worked Examples
Input
5×4m room, 2.4m ceiling, 2 coats
Result
~20 litres needed (8 × 2.5L cans)
Input
Single wall 4×2.5m, 1 coat
Result
~1 litre
Input
Full house repaint, 150m² walls
Result
~30 litres per coat
Frequently Asked Questions
How many square feet does 1 gallon cover?
Typical: 350 sq ft for one coat. Varies by paint type, surface texture, colour, and prep.
How many coats do I need?
2 coats standard. Primer + 2 coats if repainting dark to light. High-quality paint may cover in 1.5 coats.
What is primer?
Priming prepares surface, improves adhesion, reduces coats needed. Use when: new drywall, stains, major colour change.
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