Vitamin D Calculator

Vitamin D is synthesised in skin on exposure to UVB radiation (sunlight wavelength 280–315 nm). In the UK, sufficient UVB is only available from April to September (10am–3pm)

The calculator uses the standard published formula for vitamin d. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

This calculator works with inches. You can enter values in the units shown — the calculator handles all conversions internally.

The calculator applies the standard formula for this type of calculation. See the 'How It Works' steps above for the detailed formula breakdown.