About this calculator

EU rule of thumb: glazing area ≥ 10% of floor area for habitable rooms (UK Building Regs Part L). MK06 = 0.78 m², UK04 = 0.94 m², MK08 = 1.16 m² of glass.

Frequently asked questions

What does the Velux Rooflight Daylight Sizing do?

Velux size and quantity to hit 2% daylight factor for a loft room. EU rule of thumb: glazing area ≥ 10% of floor area for habitable rooms (UK Building Regs Part L). MK06 = 0.78 m², UK04 = 0.94 m², MK08 = 1.16 m² of glass.

Is the Velux Rooflight Daylight Sizing free to use?

Yes. Every calculator on Calcurly.com is free, works in your browser without sign-up, and can be embedded on your own website.

How accurate is the Velux Rooflight Daylight Sizing?

Results are calculated in real time using industry-standard formulas. Treat the output as a well-informed estimate — always cross-check with local regulations, product datasheets, or a qualified velux daylight professional before committing to a purchase or a job.

What inputs does the Velux Rooflight Daylight Sizing need?

Enter values for: Room floor (m²), Velux model. Sensible defaults are pre-filled where possible so you can start with a single change.

Can I embed the Velux Rooflight Daylight Sizing on my own website?

Yes — copy the iframe snippet at the bottom of this page, or use the Embed Generator to customise the size. The embedded version stays in sync with the live calculator on Calcurly.com.