# RayDay: Vitamin D Tracker — Less Pills, More Sunshine > Calculates optimal sun exposure times for natural Vitamin D synthesis. (iPhone/iPad app by Jakub Laszczyk.) - Source: https://appshunter.io/ios/app/rayday-vitamin-d-tracker/id6761286896 (this page in markdown: same URL + `.md`) - Developer: [Jakub Laszczyk](https://appshunter.io/developer/568719342) - Category: Health & Fitness, Weather - Price: Free with in-app purchases - Rating: 3.00/5 from 2 App Store ratings - Age rating: 4+ - Requires: iOS 17.0 · 26 MB - Languages: American English, Arabic, Catalan, Croatian, Czech, Danish, Dutch, Finnish, French (France), German (Germany) and 23 more - Released: 2026-04-03 - Data updated: 2026-08-20 - Monetization: free - User reviews in markdown: https://appshunter.io/ios/app/rayday-vitamin-d-tracker/id6761286896/reviews.md ## What is RayDay? 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: support@jakubl.com X: @jakublaszczyk ## Key features - D-Window Calculator - Live Solar Path visualization - 7-Day D-Window Forecast - Skin Type Personalization - Smart Sun Exposure Notifications - Real-time UV Index & Atmospheric Data - Home Screen Widget ## Pricing and in-app purchases Base price: Free. **Subscriptions** | Subscription | Price | Period | | --- | --- | --- | | RayDay Yearly | $24.99 | per year | | RayDay Weekly | $4.99 | per 7 days | | Early Supporter Yearly | $24.99 | per year | ## Frequently asked questions about RayDay ### 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. ## Version history (last 4 releases) ### 1.3.0 — 2026-07-16 • 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 ### 1.2.1 — 2026-06-24 You can now send feedback right from the app. Head to Settings, then Send feedback, to share ideas or report a problem. Plus small fixes and polish under the hood. ### 1.2.0 — 2026-06-18 Big update: RayDay is now built around natural Vitamin D. • Questionnaire-style onboarding tailors your sun window to your skin type, age, and lifestyle • Year-view calendar shows when winter shuts the D-Window at your latitude • Smart notifications keep you on track, even through long no-sun stretches • Optional AI skin-type detection from a quick photo • Refreshed look across every screen Send us feedback right from inside the app. ### 1.0 — 2026-04-03 No release notes. ## More apps by Jakub Laszczyk - [Color Shift Free](https://appshunter.io/ios/app/color-shift-free/id606341358) - [KetoSnap: Keto Diet Tracker](https://appshunter.io/ios/app/ketosnap-keto-diet-tracker/id6758585273) - [Plates: Gym & Workout Tracker](https://appshunter.io/ios/app/plates-gym-and-workout-tracker/id6758921527) - [Mushroom Hunter: AI Identifier](https://appshunter.io/ios/app/mushroom-hunter-ai-identifier/id6759995302) - [Fasting Timer: Nova Fast](https://appshunter.io/ios/app/fasting-timer-nova-fast/id6761011600) All apps by Jakub Laszczyk: https://appshunter.io/developer/568719342 ## Related topics [vitamind app](https://appshunter.io/ios/topics/vitamind-app) · [vitamin d](https://appshunter.io/ios/topics/vitamin-d) --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-20.*