Latest reviews, United States App Store.
★★★★★Aug 15, 2026
Inaccurate AM SunWhen I am outside in August for 2 hours beginning at sunrise, this early-morning window produces little to no meaningful vitamin D in the US zone 8 (34°N).
Yet, this tracker has me at 2000 IU.
Vitamin D synthesis requires UVB (roughly 290–315 nm). These short wavelengths are strongly absorbed and scattered when the sun is low because the path through the atmosphere (and ozone) is much longer. Practical thresholds for useful vitamin D production are generally solar elevations above ~35–45° (when your shadow is shorter than your height is a common rough guide, corresponding to ~45°). Below that, UVB is minimal or effectively absent for cutaneous vitamin D production even under clear skies.
★★★★★Jul 14, 2026
Love it!Need Apple Watch version tho
★★★★★Jul 2, 2026
Total LifesaverAvoid overusing toxic sunscreen with this app. Works very consistently. Most valuable free app on my phone.
★★★★★Jun 24, 2026
BuggyConstantly pauses itself when it should be running in the background
★★★★★Apr 15, 2026
REQUEST: Add field to dataWhen Sun Day entries get pulled into the Foodnoms app from Apple Health it uses the ‘Source: Sun Day’ field from the structured data as the title. I think if you added ‘Food Type: Sunlight’ or something like that it would improve how this displays in other apps.
★★★★★Mar 11, 2026
Best app for vitamin dTracks
1. how long you can be outside
2. Clothes you are wearing
3. Whether you’re wearing sunscreen or not
4. Skin tone
5. IU’s you getting
6. Etc
And then warns you if it’s not light enough out and you should take vitamin d
This is clearly the best app, I’ve seen other apps, this one is better and it’s free just get it.
