SUNniDAY

SUNniDAY tracks real-time UV index and estimates vitamin D production from sun exposure, personalised to your skin type, clothing, and sunscreen.

Know your burn limit before you burn. See how much vitamin D you're synthesising minute by minute. Log past sessions and review your vitamin D history over time.

Features: • Live UV index from your location • Vitamin D synthesis calculator • Skin type, clothing & sunscreen adjustments • Cloud cover override to fine-tune readings • Log past sun exposure sessions • Vitamin D history chart with body-store trend • Sunrise, sunset and moon phase • Apple Health integration • Home screen widget

Based on Sun Day by Jack Dorsey (github.com/jackjackbits/sunday), released into the public domain.

Medical disclaimer: SUNniDAY is for general informational and educational purposes only. It is not a medical device and does not provide medical advice, diagnosis, or treatment. All vitamin D and UV figures are modelled estimates, not measurements. Do not use this app to make medical decisions. Always seek the advice of your physician or other qualified health provider before making decisions about sun exposure, vitamin D supplementation, or any health condition — and use this app only in addition to, not as a substitute for, professional medical advice.