RayDay: Vitamin D Tracker
Jakub Laszczyk Health & Fitness iPhoneiPadiPod touch
RayDay: Vitamin D Tracker is a free Health & Fitness app for iPhone and iPad by Jakub Laszczyk. Rated 3.0/5 from 2 ratings. Requires iOS 17.0.
- Rating
- 3.0
- 2 ratings
- Price
- Free
- on the App Store
- Size
- 30 MB
- Age 4+
- Updated
- Sep 25
- 2026 · v1.4.0
Screenshots
About RayDay: Vitamin D Tracker
I built RayDay after years of working indoors left me Vitamin D deficient. The fix wasn't another bottle of pills. It was knowing exactly when the sun was high enough so my body could make Vitamin D the way it always has: naturally, on its own. That's all RayDay does: it tells you your daily sun window, personalized to where you live and your skin type, so you can get Vitamin D the way your body was built to. FEATURES: • D-Window Calculator: know exactly when Vitamin D production is possible today and tomorrow • Live Solar Path: a beautiful animated arc showing the sun's position, sunrise, sunset, and the highlighted D-Window • 7-Day Forecast: see your D-Window for the coming week • Skin Type Personalization: your Fitzpatrick type determines how fast you make Vitamin D • Smart Notifications: get alerted before optimal sun days, plus a heads-up when winter's first D-Window returns • Atmospheric Data: real-time UV index, cloud cover, humidity, and altitude • Phase-Aware Design: app colors shift with the time of day. Dawn, daytime, sunset, and night • Home Screen Widget: a quick glance at your D-Window status • Works Worldwide: 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 Fitzpatrick skin type to recommend exposure durations that hit your daily IU goal without overexposure. Some features require a paid subscription. DISCLAIMER: RayDay is for educational purposes only. Consult a healthcare professional before changing Vitamin D supplementation or sun exposure habits. --- LEGAL: Privacy Policy: http://www.jakubl.com/privacy.html Terms of Use (EULA): http://www.jakubl.com/terms.html SUPPORT: [email protected] X: @jakublaszczyk
What’s new
Version 1.4.0 · Updated September 25, 2026
Log your supplements, not just your sun. At higher latitudes the sun spends months too low to make vitamin D. RayDay now lets you record what you take on those days, so your daily total reflects both sources. • Log sun or supplements from the Today tab, with a 10-second undo • One daily total, with sun always counted first • History now shows a calendar of your year: gold for sun days, blue for supplement days, and a quieter shade for days the sun was never high enough • Stacked charts break down the last 7 and 30 days by source • Optional evening check-in, only ever on days the sun does not reach 35° where you are • New Reminders section in Settings to turn any notification off • Switch between IU and µg anywhere doses are shown Also fixed: notifications were silently failing to schedule for anyone who had already granted permission on an earlier launch. They work again.
App privacy
The developer, Jakub Laszczyk, reported these privacy practices to Apple.
Data Linked to You
The following data, which may be collected and linked to your identity, may be used for the following purposes:
- Contact Info: Email Address
Used for: App Functionality
Data Not Linked to You
The following data, which may be collected but is not linked to your identity, may be used for the following purposes:
- Purchases: Purchase History
- User Content: Other User Content
- Usage Data: Product Interaction, Other Usage Data
- Diagnostics: Other Diagnostic Data, Crash Data
Used for: Analytics, Product Personalization, App Functionality
Alternatives to RayDay: Vitamin D Tracker
Looking for apps like RayDay: Vitamin D Tracker? Here are 6 similar apps on the App Store. The highest rated is Vitamin D Window Widget (5.0/5), and all 6 are free to download.
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Vitamin D Window Widget
5.0
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Rays: Auto Vitamin D Tracking
4.4
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Tan Tracker: UV Index & Timer
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Tan Tracker - Suntan
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SunLove - UV Index & Tanning
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Sunshine D3
| App | Rating | Price | Last updated | Compare |
|---|---|---|---|---|
| RayDay: Vitamin D Tracker | 3.0 / 5 (2 ratings) | Free | September 25, 2026 | |
| Vitamin D Window Widget | 5.0 / 5 (2) | Free | Aug 12, 2026 | Compare |
| Rays: Auto Vitamin D Tracking | 4.4 / 5 (7) | Free | Aug 28, 2026 | Compare |
| Tan Tracker: UV Index & Timer | – | Free | Jun 4, 2026 | Compare |
| Tan Tracker - Suntan | 4.0 / 5 (1) | Free | Aug 28, 2025 | Compare |
| SunLove - UV Index & Tanning | – | Free | Aug 14, 2025 | Compare |
| Sunshine D3 | – | Free | Oct 7, 2026 | Compare |