Comparison

Vitamin D Window Widget vs SolGlow

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Vitamin D Window Widget

This app displays the optimal times of day for natural vitamin D production based on your location and the sun's elevation. It offers real-time sun schedules, smart widgets for home screen access, and notifications to help you maximize your sun exposure.

Highlights
  • Real-time sun schedule
  • Smart widgets
  • Daily schedule updates
  • Dynamic Island countdown
  • Location-based calculations
  • Offline functionality
  • Solar-themed design
Features
Read full description

Vitamin D Window shows you the exact hours when sunlight is strong enough for natural vitamin D production at your location. Set up the app and the widget and enjoy the time window in a snapshot. HOW IT WORKS The app calculates solar elevation angles throughout the day using your GPS coordinates. When the sun is high enough above the horizon (above 45° for optimal conditions, above 30° for partial), you get a clear vitamin D time window with start and end times. FEATURES · Real-time sun schedule — sunrise, sunset, and vitamin D hours at a glance · Solar progress bar — see where you are in the day's sun cycle · Smart widgets (small, medium, large) — check your vitamin D window right from your home screen · Daily schedule — it changes depending on the time of the year · Dynamic island with live countdown of the last minutes of vitamin D in the day · Notifications — don't lose the key moments of the day · Location-based — it changes depending on your location · Works offline — no internet connection required after setup · Beautiful solar-themed design — adaptive gradients that follow the sun through the day WIDGETS THAT KEEP YOU INFORMED Add a widget to your home screen and instantly see today's vitamin D window. The small widget features a progress bar in real time as you move through the vitamin D hours. Medium and large widgets show the full sun timeline with sunrise, sunset, and vitamin D periods. After sunset, widgets automatically switch to show tomorrow's schedule — so you always know what's coming. WHO IS THIS FOR? · Health-conscious individuals who want to optimize their sun exposure timing · People living at higher latitudes where vitamin D windows are seasonal (almost all countries) · Outdoor enthusiasts planning activities around peak sun hours · Anyone curious about their local solar schedule PRIVACY FIRST Your location is used only on your device to calculate solar positions. No data is collected, stored on servers, or shared with third parties. Everything runs locally. — Solar calculations powered by the SunCalc algorithm. Vitamin D window times are based on solar elevation angles and may vary depending on individual factors such as skin type, altitude, and atmospheric conditions.

About

SolGlow

This app automatically estimates your daily vitamin D intake based on sunlight exposure, skin type, and location. It provides real-time UV index, burn-safe time remaining, and integrates with Apple Watch for effortless tracking. Features include winter mode, supplement check-ins, and advanced planning tools for Pro users.

Highlights
  • Automatic vitamin D estimation
  • Live UV index and IU-per-minute rate
  • Burn-safe time remaining with alerts
  • Winter Mode for low-sun periods
  • Supplement check-in
  • 7-day UV forecast (Pro)
  • Trip Planner for jet lag (Pro)
Features
Read full description

SolGlow turns your time outside into the number that matters: vitamin D — measured in IU, not just minutes. And it's automatic: your Apple Watch's daylight is credited to your estimate by itself — no logging, no GPS trail — and every number can show the exact math behind it. From your Time in Daylight, skin type, outfit, age, and your location's sun angle, SolGlow estimates the vitamin D you actually made today — and warns you before you burn. SUN TODAY, IN ONE ANSWER (NEW) • When today's vitamin D window opens — the same UV 3+ hours that call for sun protection • Your burn time, and the protection today's UV calls for: SPF, sunglasses, shade • Optional alerts when today's protection hours begin • Live UV index, one daily goal tuned to your life stage, and vitamin-D foods in your units SUN SAFETY THAT KNOWS YOU (NEW, FREE) • Sun Sensitivity: taking a medicine that can increase sun sensitivity? Every burn time gets a cautious margin • Snow, sand or water bounce extra UV at you — tell SolGlow and today's burn math adjusts • Monthly Skin Check: the ABCDE self-exam with a gentle reminder — a habit, never a diagnosis AUTOMATIC, AND YOU CAN SEE WHY (FREE) • True-D: SolGlow corrects the UV Index for ozone — sunburn UV isn't vitamin-D UV — and shows the cited step whenever it changes your number (Kazantzidis 2009) • Learn & Sources: plain-language guides to UV, sunscreen, winter and more, each with its studies • Ask Siri "How much sun did I get in SolGlow?" — plus Best Sun Window widgets for StandBy, Lock Screen, and Home Screen MADE FOR IPHONE DUO Open it and Today spreads into two columns, guides read like a book, and a live session stands up like a scoreboard on the picnic table. OWN THE WINTER • Winter Mode: when your latitude's noon sun can't make vitamin D, SolGlow shows where yours is coming from — and counts down to the sun's return • Free Winter Countdown widget and Apple Watch complication — works offline • Streak Shield: only physics can excuse a missed day • One-tap supplement check-in from a notification, widget, Siri, or your watch BRING YOUR HISTORY (FREE) • Import your Time in Daylight history from Apple Health in one tap — no account • Back up everything to one file and restore on a new phone SUN SESSIONS (PRO) • Direct Sun: a live burn budget that only counts down, and says plainly when to get out • Live Activity on your Lock Screen and Dynamic Island, with a sunscreen reapply timer • Morning Light, editable history, streaks, a shareable weekly recap — and the Apple Watch app PLAN AHEAD (PRO) • 7-day UV forecast with your personal best-sun windows • Annual sun plan and a jet-lag Trip Planner (timing guidance, not medical advice) KNOW YOUR LEVEL (PRO) • 25(OH)D serum estimate with a 12-week projection • Cofactors, supplement guidance, blood-test reminders, and a doctor-ready PDF/CSV report PRIVATE BY DESIGN No account. No sign-up. No analytics. No ads. Your health data, profile, and location history never leave your device — the only network call fetches a UV forecast (coordinates only, no identifier). Optional backup goes to your own iCloud, never to us. FREE TO TRY — THEN PICK YOUR PLAN Every feature free for 14 days. Then choose your SolGlow Pro: $9.99 per year, auto-renewing until you cancel — or Lifetime: one purchase, yours forever, Family Sharing included. The free tier keeps today's tracking and all safety features, always. SolGlow estimates are educational, not medical advice. Always consult your clinician about vitamin D supplementation and blood testing. SolGlow Pro Annual is an auto-renewing subscription: $9.99 per year, charged to your Apple ID at purchase confirmation. It renews unless cancelled at least 24 hours before the period ends. Manage or cancel in your App Store settings. SolGlow Pro Lifetime is a one-time purchase that never renews. Privacy Policy: https://twisteddatastudios.com/privacy.html Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Screenshots

Vitamin D Window Widget4 screens
SolGlow4 screens

Verdict

The call

The clearest difference is review sentiment: Vitamin D Window Widget at 100% against SolGlow's 50%. Vitamin D Window Widget also leads on rating (5.0 vs 3.7) and in-app purchases (none vs 2). SolGlow's advantage is device support (3 vs 1). On price, ratings volume, update cadence and ads there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. SolGlow sells 2 in-app purchases, starting at $9.99 per year. Vitamin D Window Widget asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Vitamin D Window Widget holds the better App Store score, 5.0 against 3.7. Both are backed by a comparable volume of ratings — 2 and 3 respectively. Written reviews point the same way: 100% of Vitamin D Window Widget's written reviews are positive against 50% of SolGlow's.

UpkeepUpdate frequency

Vitamin D Window Widget ships an update every 2 weeks, SolGlow every 10 days. Both last shipped on October 31, 2026.

Scorecard5 real differences · 5 level
Vitamin D Window Widget versus SolGlow: the parameters behind the verdict, then further details
ParameterVitamin D Window WidgetSolGlow
PriceFreeFree
Rating5.0 (2 ratings) — better3.7 (3 ratings)
Positive reviews100.0% of reviews — better50.0% of reviews
Number of ratings23 — better
Update frequencyEvery 2 weeksEvery 10 days — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree — betterFreemium
DevicesiPhoneiPhone, iPad, Apple Watch — better
Requires iOS18.017.2 — better
Further details — not scored
Size2 MB10 MB
Age rating4+12+
DeveloperAirhopping, SLMichael Smith

Customer experience

Vitamin D Window Widget

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews2 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

SolGlow

All ratings3 ratings
Positive66.7%
Neutral0.0%
Negative33.3%
Written reviews2 reviews
Positive50.0%
Neutral0.0%
Negative50.0%

In-app purchases

None

Vitamin D Window Widget

No in-app purchases

2 purchases

SolGlow

Subscriptions1
  • SolGlow Pro Annual$9.991 Year
One-time1
  • SolGlow Pro$29.99

Questions

Is Vitamin D Window Widget free?
Vitamin D Window Widget is free to download, with no in-app purchases.
Is SolGlow free?
SolGlow is free to download, with in-app purchases available.
Which has better reviews, Vitamin D Window Widget or SolGlow?
Vitamin D Window Widget is rated higher. Vitamin D Window Widget averages 5.0 out of 5 from 2 ratings, while SolGlow averages 3.7 from 3 ratings.
Do Vitamin D Window Widget or SolGlow have ads?
Neither Vitamin D Window Widget nor SolGlow shows ads.
Which is updated more often, Vitamin D Window Widget or SolGlow?
Vitamin D Window Widget ships an update every 2 weeks, and SolGlow every 10 days. Most recently, Vitamin D Window Widget was updated on October 31, 2026 and SolGlow on October 31, 2026.

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