TanMeter App Store

TanMeter tool

Balance Vitamin D and Sunburn Risk

TanMeter calculates the minimum sun exposure minutes needed for adequate vitamin D synthesis at your latitude and skin type—without crossing into burn territory.

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How it works

  1. Enter your skin type, latitude or city, and current season.
  2. View TanMeter's vitamin D synthesis window in minutes of unprotected arm exposure.
  3. Compare the vitamin D window against your burn risk threshold.
  4. Find the safe overlap zone where you get D without damaging skin.
  5. Log sessions in TanMeter to track weekly vitamin D sun time.

FAQ

How much sun do I need for vitamin D?

Most people need 10–30 minutes of midday sun on arms and legs several times per week. TanMeter adjusts for skin type and latitude.

Can I get vitamin D through sunscreen-covered skin?

SPF 30 blocks about 97% of UVB—the vitamin D wavelength. TanMeter recommends brief unprotected exposure within your safe window.

Should I rely on sun alone for vitamin D?

TanMeter recommends sun as a supplement to diet and D3 supplements, especially above 37° latitude in winter months.