How to Calculate Window Calculator
What is Window Calculator?
A window cost and area calculator helps estimate the number of windows needed for a new building, replacement cost for existing windows, or the glazing area for planning and building regulations compliance.
Step-by-Step Guide
- 1Measure each window opening: width × height = area in m²
- 2Sum all window areas
- 3Building regulations: windows + roof lights typically cannot exceed 25% of floor area for heat loss reasons
- 4Cost estimate: standard double-glazed window: £300–800 supply-only depending on size
Worked Examples
Input
6 windows avg 1.2m × 1.0m
Result
7.2m² total glazing
Check vs floor area for compliance