Paint Calculator
Work out how many liters or gallons of paint you need from area, coats, coverage and waste.
Inputs
Check the paint can or data sheet
Result
Paint required
11L
2.91 US gal
- Area to cover (all coats)
- 100m²
- Paint before waste
- 10L
Formula
Paint = Area × Coats ÷ Coverage × (1 + Waste ÷ 100)
How it works
The amount of paint you need depends on the surface area, how many coats you apply and how far each liter (or gallon) spreads. The calculator multiplies area by coats, divides by the coverage and adds a waste allowance for rollers, trays and touch-ups.
- Measure the area to paint. For walls, multiply width by height and subtract large windows and doors.
- Find the coverage on the can or the product data sheet, often 8–12 m²/L (about 350–400 ft²/gal).
- Add 5–15% waste. Rough or porous surfaces need more.
Add the price per liter or gallon to estimate the total cost.
Formula
- Paint = Area × Coats ÷ Coverage × (1 + Waste ÷ 100)
- Cost = Paint × Price per unit
Example
A 50 m² room, two coats
- 150 m² × 2 coats = 100 m² to cover
- 2100 m² ÷ 10 m²/L = 10 L
- 310 L × 1.10 waste = 11 L
Buy 11 liters (about 2.91 US gallons).
Frequently asked questions
How many coats of paint do I need?
Two coats is standard for most walls. A single coat can work when repainting the same color; a strong color change or a fresh surface may need a primer plus two coats.
How much area does a liter of paint cover?
Typical interior wall paint covers 8–12 m² per liter per coat. Always check the manufacturer's figure — primers and textured paints cover less.
Does it work for metal and industrial coatings?
Yes, as long as you use the coverage from the coating's data sheet. For dry film thickness-based specifications, convert the theoretical spread rate to area per liter first.