Skylight Calculator
Calculate skylight and roof lantern costs, sizes and thermal performance for fixed, opening, dome and lantern skylights with Part L U-value checking.
Fixed flat is most common
Triple for better insulation
Internal dimension
Internal dimension
Number of skylights
How We Calculate This
This calculator estimates skylight costs based on type, size, glazing and quantity.
The formula
Total = (Unit Price × Size Factor × Glazing Multiplier × Qty) + Kerb Kits + Installation
- Base prices vary by skylight type
- Size factor increases for units over 1 m²
- Triple glazing adds ~35% to unit cost
- Daylight gain = Area × 3 (vs vertical glazing)
Frequently Asked Questions
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Last updated: March 2026
All calculations are estimates. Verify with your supplier.