UV Tracker & Vitamin D: RayDay
Safe Tanning, SPF & Sun Timer
Free · Designed for iPad. Not verified for macOS.
Your personal sun seeker — track vitamin D, UV index & safe tanning time. Know when rays are strong enough, protect your skin with SPF tracking, and earn sunshine badges.
RayDay is the ultimate sun seeker's companion — a vitamin D and UV tracker that tells you exactly when the sun is high enough each day for your body to produce vitamin D naturally.
Using NOAA solar position algorithms and real-time atmospheric data, RayDay calculates your personal "D-Window" — the precise time between sunrise and sunset when UVB rays can penetrate the atmosphere (sun altitude above 35°). No guessing, no generic advice — just science-based timing personalized to your location and skin type.
FIND YOUR D-WINDOW
Know exactly when vitamin D production is possible. RayDay shows today's and tomorrow's D-Window with a beautiful animated solar path arc. Watch the sun beam across the sky from morning daylight through golden hour to sunset.
TRACK VITAMIN D LIVE
Start a sun session timer and track your vitamin D production in real-time. See your IU accumulate with a stunning progress ring, monitor your UV index exposure, and know exactly when you've reached your daily goal.
PROTECT YOUR SKIN
Stay safe in the sunshine with a built-in burn countdown timer. RayDay personalizes everything to your Fitzpatrick skin type (I–VI), clothing level, and SPF sunscreen — so you get the glow without the burn. Safe tanning starts with knowing your limits.
PLAN YOUR WEEK
Check the 7-day forecast to see your D-Window for the coming week. Each day shows the start time, duration, and peak sun angle so you can plan outdoor sessions when rays are strongest.
EARN SUN BADGES
Stay motivated with 20 collectible badges. Earn streaks, session milestones, IU achievements, and special badges like Globe Trotter and Golden Hour. Your sunshine journey, gamified.
MORE FEATURES
• Live Solar Path — Animated arc showing sun position from sunrise through sunset
• Atmospheric Dashboard — Real-time UV index, cloud cover, altitude, and humidity
• Smart Notifications — Get a notify alert 15 minutes before your D-Window opens
• Home Screen Widget — Quick glance at your D-Window and sun status
• SPF & Sunscreen Support — Factor in your sunscreen protection level
• Snow & Sand Albedo — Automatic UV reflection adjustments for snow, sand, and water
• 30 Languages — Fully localized for worldwide use
• Phase-Aware Design — App colors shift with daylight: dawn sunglow, morning beam, sunset glow
• Works Everywhere — Accurate for any latitude, including polar regions
HOW IT WORKS
RayDay uses NOAA solar position algorithms to calculate the sun's altitude throughout the day. When the sun crosses 35° above the horizon, UVB rays penetrate the atmosphere — that's your D-Window for vitamin D synthesis. The app factors in your skin type, clothing, and SPF to recommend safe exposure durations using Holick's Rule for vitamin D production.
DISCLAIMER: RayDay is for educational and informational purposes only. It is not a medical device. Consult a healthcare professional for advice about vitamin D supplementation and sun exposure. Studies referenced: Holick MF (2007, PMID: 17634462), Webb AR (2006, PMID: 16529140).
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LEGAL:
Privacy Policy: http://www.jakubl.com/privacy.html
Terms of Use (EULA): http://www.jakubl.com/terms.html
SUPPORT:
support@jakubl.com
X: @jakublaszczyk
Ratings & Reviews
The developer, Jakub Laszczyk, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Linked to You
The following data may be collected and linked to your identity:
- Contact Info
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Purchases
- User Content
- Usage Data
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Jakub Laszczyk
- Size
- 23.1 MB
- Category
- Health & Fitness
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
English and 32 more
- English, Arabic, Catalan, Croatian, Czech, Danish, Dutch, Finnish, French, German, Greek, Hebrew, Hindi, Hungarian, Indonesian, Italian, Japanese, Korean, Malay, Norwegian Bokmål, Polish, Portuguese, Romanian, Russian, Simplified Chinese, Slovak, Spanish, Swedish, Thai, Traditional Chinese, Turkish, Ukrainian, Vietnamese
- Age Rating
4+
- 4+
- Copyright
- © 2026 Jakub Laszczyk