Vitamin D Calculator

How this vitamin D check works

Your body makes vitamin D from sunlight on skin, so the main drivers of low levels are how much daylight you get, your skin tone, the season and latitude where you live, and your age. This tool weighs those factors into a simple risk estimate and shows the general daily reference intake for your age group. It does not prescribe a dose — that's a conversation for you and your doctor, ideally after a blood test.

Test, don't guess

The only way to truly know your vitamin D status is a 25(OH)D blood test. If your risk here is moderate or higher, it's worth asking your doctor about one. Our Vitamins & Minerals guides — including a full guide to vitamin D — explain what the results mean.