Vitamin D from Sun Exposure
Light skin: ~10-15 min midday sun produces 1000-3000 IU. Darker skin needs 3-6× longer.
Result
Estimated IU
188 IU
31% of 600 IU RDA.
- Minutes15
- Skin tonemedium (0.5×)
- Body % exposed25%
- Seasonsummer (1×)
- IU produced188
- RDA target600 IU/day (NIH)
- % of RDA31.3%
Step-by-step
- Base = 15 × 100 IU/min (fair, full body, summer) = 1,500.
- Adjusted = base × skin × exposed × season = 188 IU.
How to use this calculator
- Minutes + skin + body % + season.
About this calculator
Sunlight UVB triggers vitamin D production in skin. Estimates vary widely by latitude, season, time of day, skin tone, and exposed area. Rough rule: light skin, 25% body, 15 min midday summer ≈ 1000-2000 IU. Dark skin needs 3-6× longer for same dose. Above 35° latitude (US north of Atlanta), winter sun is too weak — supplementation usually needed Oct-Apr. NIH RDA: 600 IU/day adults; 800 IU 70+. Sources: NIH ODS, Holick (2007).
Frequently asked
Above 35° latitude (US north of Atlanta), winter UVB too weak. Supplement Oct-Apr.
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