RayDay: Vitamin D Tracker
Less Pills, More Sunshine
About
This app calculates your daily window for natural Vitamin D production based on your location and skin type. It provides solar path visualization, forecasts, and atmospheric data to help you optimize sun exposure safely.
What's New in RayDay
1.3.0
July 16, 2026
• Widget now shows the live UV index and solar noon • New vitamin D history charts: track your last 7 and 30 days • Cleaner, decluttered interface • Bug fixes and performance improvements
MoreDeveloper apps
FAQ
What is RayDay's D-Window?
RayDay's D-Window is the period each day when the sun's altitude is above 35° and UVB rays can penetrate the atmosphere for Vitamin D synthesis. The app calculates this window based on your location and skin type.
How does RayDay personalize sun exposure?
RayDay uses your Fitzpatrick skin type to recommend exposure durations. This helps you achieve your daily Vitamin D IU goal without risking overexposure.
Does RayDay work worldwide?
Yes, RayDay is designed to be accurate for any latitude, including polar regions. It uses NOAA solar position algorithms for precise calculations.
What atmospheric data does RayDay provide?
The app offers real-time UV index, cloud cover, humidity, and altitude. This information helps you understand current conditions affecting sun exposure.
Can I get alerts from RayDay?
Yes, RayDay offers smart notifications. You'll receive alerts before optimal sun days and a reminder when winter's first D-Window returns.
What is RayDay's rating and update frequency?
RayDay has a rating of 3.0 stars from 2 ratings. The app was last updated on June 24, 2026, indicating recent development activity.
Is RayDay available on all devices?
RayDay is supported on iPhone and iPad devices. It is rated for ages 4 and up.
Does RayDay have ads?
No, RayDay is ad-free. It is a free application with no advertisements to interrupt your experience.