Sun Exposure Calculator

Estimate recommended sun exposure time from skin type, SPF, UVI, and vitamin D goal.

1.0M uses Updated · 2026-05-24 Runs locally · zero upload
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How to Use Sun Exposure Calculator

Select the skin type closest to the user, enter the sunscreen SPF, current UV index, and vitamin D target. The calculator returns a conservative exposure time and highlights caution when UV index is high. It is for education and planning, not medical advice.

Formula & Theory - Sun Exposure Calculator

The calculator starts with a skin-tolerance factor and divides it by UV pressure:

SPF correction = √SPF
vitamin D factor = vitamin D goal / 600
recommended minutes = skin tolerance / (UVI × SPF correction) × vitamin D factor

Lighter skin types use lower tolerance factors and darker skin types use higher ones. Higher UVI shortens the recommended time. A higher vitamin D target increases the time, but the result is clamped to a practical range because sunburn risk does not disappear simply because a vitamin target is higher.

Use Cases for Sun Exposure Calculator

  • Outdoor breaks - Plan short sunlight breaks while watching UV intensity.
  • SPF comparison - See how higher SPF changes estimated exposure time.
  • Health education - Discuss why skin type and UVI affect sunburn risk.

When UVI is high, use the result as a ceiling, not a target to chase.

Frequently asked questions about Sun Exposure Calculator

Is this medical advice?

No. It is an educational estimate; skin conditions, medication, altitude, reflection, and local UV warnings can change safe exposure.

Why does SPF use a correction instead of multiplying time by SPF?

The calculator uses a conservative square-root correction so SPF does not create unrealistically long exposure times.

Is my data stored?

No. All calculations happen in your browser; nothing is sent to a server.