D-Fine

Know exactly how much vitamin D you get from sunlight, food, and supplements — calculated for your skin, your location, and the time of day. One clear number, every day.

Know exactly how much vitamin D you're getting. Every day.

D-Fine tracks your vitamin D from three sources — sunlight, food, and supplements — and tells you if it's enough, based on your skin, your location, and the time of day.

THE PROBLEM

Vitamin D deficiency is one of the most common in the world, even among people who spend time outdoors. The issue isn't laziness. It's that no one can tell how much sun they actually need. It depends on where you live, the time of day, your skin type, what you're wearing. You can't figure that out by feel.

THREE SOURCES, ONE NUMBER

Until now, there was no way to see all the sources of vitamin D together. D-Fine combines sunlight, food, and supplements into a single daily figure — your IU today versus your personalized daily target. If you're taking a supplement, you'll finally know whether it's the right dose for you, today, in this season.

WHAT D-FINE DOES

Sunlight — D-Fine reads your time in daylight from your iPhone and Apple Watch, then calculates the IU your skin actually synthesized, factoring in UV index, sun angle, cloud cover, your Fitzpatrick skin type, how much skin is exposed, and any SPF you logged.

Food — Log meals containing vitamin D. D-Fine adds the IU to your daily total.

Supplements — Track your daily supplement dose. D-Fine warns you before you cross safe thresholds.

WHO IT'S FOR

People who live far from the equator, work indoors, have darker skin, are over 50, or just want to stop guessing.

PRIVACY

All processing happens on your device. Your profile syncs through your private iCloud container — only you can read it. Anonymous usage data is strictly opt-in (default OFF), uses a non-persistent install ID, and contains no Apple identifiers or personal information.

APPLE WATCH

With an Apple Watch, D-Fine measures your Time in Daylight continuously and passively, the way Apple intended. Without it, the app falls back to estimating from outdoor workouts and UV conditions — still useful, just less precise.

D-Fine is not a medical device. It's a science-based calculation tool to help you understand your vitamin D intake. For medical concerns, talk to your doctor.

Privacy Policy: https://d-fine.app/privacy Support: https://d-fine.app/support