How the calculation works
The formulas
Add walls and deduct rectangular openings. Enter the product’s stated coverage for one coat, the number of coats, and container options. The main purchase result uses the first option; the table compares each size separately.
Net area = Σ(wall width × height) − Σ(opening area × count)
Litres = net area × coats ÷ coverage
Containers = ceil(litres ÷ container litres)
Assumptions to check
- Coverage is entered in m² per litre per coat; substrate losses are reflected in your chosen coverage.
- Each comparison buys one container size only; mixed-size purchase combinations are not optimized. Zero prices mean unpriced.
A worked example
30 m², two coats, and 10 m²/L require 6 L. With 2.5 L containers, buy 3 containers (7.5 L).