Comparison

D vs BigDose

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

Head to head
About

D

Features
Read full description

Know exactly how much vitamin D you're getting. Every day. D-Fine tracks your vitamin D from three sources β€” sunlight, food, and supplements β€” and tells you if it's enough, based on your skin, your location, and the time of day. THE PROBLEM Vitamin D deficiency is one of the most common in the world, even among people who spend time outdoors. The issue isn't laziness. It's that no one can tell how much sun they actually need. It depends on where you live, the time of day, your skin type, what you're wearing. You can't figure that out by feel. THREE SOURCES, ONE NUMBER Until now, there was no way to see all the sources of vitamin D together. D-Fine combines sunlight, food, and supplements into a single daily figure β€” your IU today versus your personalized daily target. If you're taking a supplement, you'll finally know whether it's the right dose for you, today, in this season. WHAT D-FINE DOES Sunlight β€” D-Fine reads your time in daylight from your iPhone and Apple Watch, then calculates the IU your skin actually synthesized, factoring in UV index, sun angle, cloud cover, your Fitzpatrick skin type, how much skin is exposed, and any SPF you logged. Food β€” Log meals containing vitamin D. D-Fine adds the IU to your daily total. Supplements β€” Track your daily supplement dose. D-Fine warns you before you cross safe thresholds. WHO IT'S FOR People who live far from the equator, work indoors, have darker skin, are over 50, or just want to stop guessing. PRIVACY All processing happens on your device. Your profile syncs through your private iCloud container β€” only you can read it. Anonymous usage data is strictly opt-in (default OFF), uses a non-persistent install ID, and contains no Apple identifiers or personal information. APPLE WATCH With an Apple Watch, D-Fine measures your Time in Daylight continuously and passively, the way Apple intended. Without it, the app falls back to estimating from outdoor workouts and UV conditions β€” still useful, just less precise. D-Fine is not a medical device. It's a science-based calculation tool to help you understand your vitamin D intake. For medical concerns, talk to your doctor. Privacy Policy: https://d-fine.app/privacy Support: https://d-fine.app/support

About

BigDose

Features
Read full description

Most sun apps pick a lane: vitamin D or sun safety. BigDose tracks both β€” in real time β€” so you can get outside with a plan instead of a guess. DOSE YOUR D. DEFEND YOUR SKIN. BigDose is built for people who want vitamin D from the sun and still respect their skin. We combine live Apple Weather, your skin type, sunscreen habits and sun angle to show when conditions are right for UVB β€” and when burn risk is climbing. YOUR DAILY COMMAND CENTER β€’ Vitamin D window today β€” a sun-path diagram with Apple Weather sunrise and sunset, your personal D window, total daylight and how today compares to yesterday β€’ Live UV, humidity, cloud cover, hourly and 3-day forecast from WeatherKit at your GPS β€’ Daily sun IU goal with progress from sessions, supplements and food logged separately β€” no double-counting β€’ Sun risk today when live sessions push past your personal burn threshold β€’ Recommended daily IU tuned to age, skin type and goals LIVE SUN SESSIONS THAT RESPECT BOTH GOALS Start a session when your window is open. BigDose tracks elapsed time, estimated vitamin D toward your daily target and MED (burn risk) used on a live dial. Alerts when session safety is on: β€’ Turn-over near 50% β€” rotate exposure β€’ Optional Nanny Mode adds wrap-up at 75%, guidance at 95% and a 98% reminder β€’ Stop-now at 100% MED β€” always, Nanny on or off You always end the session. We never do it for you. DOSE DNA β€” YOUR PROFILE, YOUR MATH Set Fitzpatrick skin type, typical coverage, sunscreen use, supplement defaults and a blood-level goal in ng/mL. BigDose personalizes session timing, safe max duration and safety alerts to you β€” not a generic chart. PLAN BEFORE YOU STEP OUTSIDE Session planner shows safe max duration at today’s UV, time to reach your D goal and milestone timeline. First-session guide walks new users through the dial, alerts and how to stop on their terms. PROGRESS THAT CONNECTS INTAKE TO LEVEL Log supplements and vitamin D food sources. Import labs when you have them. Progress estimates how your 25(OH)D trend is moving toward your goal using sun, pills and diet β€” with honest limits: modeled estimates, not a lab result. History keeps a ledger of sun, supplements and food by day. NOTIFICATIONS THAT MATCH YOUR STYLE Solar event reminders, next D opportunity nudges, optional AM light window alerts and session safety notifications when the app is in the background. Toggle what you want during onboarding or anytime in Settings. Nanny defaults on β€” turn it off when you want a lighter touch. SMART GUIDANCE, NOT A LECTURE Science tab explains how BigDose thinks about D and burn risk in plain language. Info buttons throughout β€” tap the (i) when you want context, skip them when you do not. BUILT FOR REAL OUTDOOR DAYS Live Activities keep an active session on your Lock Screen. Home Screen widgets surface today’s plan. Optional Apple Health import. High-contrast UI designed for glare, gloves and one-handed use outside. WHAT BIGDOSE IS β€” AND IS NOT BigDose is wellness guidance you choose to use. It is not medical advice, not a diagnosis and not a substitute for your clinician. Blood tests remain the source of truth for vitamin D status. Use shade, clothing and sunscreen beyond what any app can model. Whether you are optimizing morning light, chasing a short mid-day window or logging a supplement on a rainy day, BigDose helps you dose your D and defend your skin β€” same app, same dashboard, no false tradeoff. We ship often and read every report. Thanks for helping us make BigDose sharper every build.

Screenshots

D4 screens
BigDose4 screens

Verdict

The call

The clearest difference is iOS requirement: D at 17.4 against BigDose's 26.0. On price, ads, in-app purchases and device support there is nothing between them.

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

CostPrice Β· In-app purchases Β· Ads Β· Monetization

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Scorecard1 real difference Β· 5 level
D versus BigDose: the parameters behind the verdict, then further details
ParameterDBigDose
PriceFreeFree
Update frequencyβ€”Every 2 days
AdsNoNo
In-app purchasesNoNo
DevicesiPhone, Apple WatchiPhone, iPad
Requires iOS17.4 β€” better26.0
Further details β€” not scored
Size13 MB10 MB
Age rating4+4+
DeveloperAirbag Studio SrlGrant Perry

In-app purchases

None

D

No in-app purchases

None

BigDose

No in-app purchases

Questions

Is D free?
D is free to download, with no in-app purchases.
Is BigDose free?
BigDose is free to download, with no in-app purchases.
Do D or BigDose have ads?
Neither D nor BigDose shows ads.

Other comparisons