SolGlow turns Apple Watch's Time in Daylight, your location, and your skin type into a real estimate of the vitamin D you produced today — supplements, food, and sun, all in one place. Nothing leaves your device but a forecast lookup.
SolGlow Pro used to come one way. Now there are two: $9.99 a year, or $19.99 once and it's yours for good. Nothing is held back on the yearly plan, and if you already own the lifetime unlock nothing changes for you — you keep it, and you'll never see a renewal prompt. See both plans →
$9.99 per year, auto-renewing until you cancel — or the one-time $19.99 unlock, which never renews and never expires. Family Sharing comes with the lifetime unlock.
The unlock screen shows both plans side by side with each one's price, length and exact renewal terms at the moment you choose — not buried afterwards.
Subscribers get a clear status line and a Manage Subscription link right in their profile. Lifetime owners see their unlock, and nothing that looks like a bill.
A redesigned app icon and an animated opening built from SolGlow's own sun mark, so the app you tap and the app that opens finally look like each other.
That same sun mark now replaces the generic system symbol across every widget, the Lock Screen and the Apple Watch — twenty places that used to borrow someone else's icon.
Purchases restore more reliably on a new device or after a reinstall, and VoiceOver no longer reaches controls hidden behind the opening animation.
The UV Index measures sunburn, not vitamin D — and the two pull apart whenever ozone is high or the sun sits low. SolGlow's new True-D engine re-weights UV into true vitamin-D UV using total-column ozone and sun angle, with the studies named on screen. Your free estimates only ever get more honest — never inflated.
SolGlow re-weights the UV Index for ozone and sun angle into true vitamin-D UV — because sunburn UV isn't vitamin-D UV. Your free estimates only ever get more honest, never inflated. (Kazantzidis 2009, CIE action spectrum)
On days ozone changed your number, “See how this was calculated” adds a new cited step showing exactly how much — a high-UV day can still be a weak vitamin-D day, with the math on screen. Free.
SolGlow now speaks German, Spanish, and Japanese everywhere — the app, every widget, the Apple Watch app and complications, Siri answers, and even the system permission prompts.
Widgets, the Watch complication, and Siri now roll over at midnight instead of showing yesterday's sun as today's. If a number is stale, SolGlow says “open to refresh” — never old data as live.
Permission requests come one at a time, in context. The paywall shows real Restore progress, explains Family Sharing “Ask to Buy” approvals, and a locked widget now opens the unlock screen directly.
Manual sun logging from an empty history, a serum estimate that stays neutral until you anchor it with a blood test, clearer colors in bright light, and offline trip planning that shows the physics fallback instead of an error.
Anything you've already unlocked stays yours. Estimates are educational, not a diagnosis. See SolGlow Pro pricing →
When the noon sun at your latitude can't make vitamin D, SolGlow doesn't go quiet — it changes shape, shows where your vitamin D is coming from, and counts down to the sun's return. Everything from the v1.6 winter release, now on your phone.
When your latitude's noon sun can't clear the vitamin-D threshold, a D-Maintenance view shows where your vitamin D is really coming from — supplements, food, and daylight for your body clock — with a “Sun returns” countdown and the physics on screen. Free.
“Days until the sun makes vitamin D again at your latitude.” A free widget for the Home Screen, Lock Screen, and StandBy, plus an Apple Watch complication. It even counts down offline.
Winter can't break your streak. When physics says the sun couldn't make vitamin D that day, the miss is excused and your streak freezes instead of breaking — only physics excuses a day, clouds and travel never do. Free.
Mark your supplement “Taken” straight from a notification, an interactive widget, Siri, or your Apple Watch — without opening the app. Your goal counts it either way. Free.
Own a UVB sun lamp? Log sessions the way you log sun — counted against your lamp maker's own stated limit and credited from their published figures, hard-capped and labeled as estimates. The overexposure warning is free for everyone.
Optional encrypted backup to your own iCloud (never our servers), a clearly-labeled clear-sky estimate when you're offline, September Head-Start and Hold the Line season planning, and Year in the Sun — a shareable recap of your whole year.
SolGlow combines what your Apple Watch already measures (Time in Daylight) with the physics of where you are and the biology of your skin — and folds in your supplements and food. It's an estimate, but a transparent one: every input is shown.
Reads the daylight your Watch already records. SolGlow never modifies it — it only reads.
Computes your sun's elevation and the local UV factor for accurate vitamin-D synthesis windows.
Skin-type-aware synthesis and burn-time calculations — Type I through VI all dialed in.
Forecasted UV combined with your time outside warns you before your skin's threshold is crossed.
A calendar of your actual sun, supplement, and dietary vitamin D — with location-aware attribution for travel days.
Today's IU, sun minutes, and daily-goal progress at a glance — refreshed in the background.
Glanceable Progress, Serum, and Forecast cards on the wrist. Pulls Time in Daylight straight from watchOS.
Heaney/Veith dose-response converts your daily IU into projected 25(OH)D in ng/mL.
USDA FoodData Central built in. Salmon, eggs, fortified milk — all rolled into your daily total.
SolGlow makes exactly one network call: a UV forecast lookup to Open-Meteo with just a latitude and longitude — no name, no account, no device ID. Apple Health data, your profile, your food log, your location history — all of it stays on your iPhone in iOS app-private storage, pruned automatically after 60 days.
Free download, then pick the plan that suits you. No ads, ever. Requires iOS 17.2 or later; Apple Watch (watchOS 10+) recommended for the most accurate Time-in-Daylight data.
Same features either way — nothing is held back on the yearly plan
Today's tracking, every safety alert, the Apple Watch app and widgets stay free — and every new install gets 14 days with everything unlocked. That preview is SolGlow's own, not a subscription trial: nothing is charged, and nothing starts when it ends.
SolGlow Pro Annual is an auto-renewing subscription: $9.99 per year, charged to your Apple ID at confirmation of purchase. It renews automatically unless cancelled at least 24 hours before the end of the current period. Manage or cancel it any time in your App Store account settings. SolGlow Pro Lifetime is a one-time purchase and never renews. See our Privacy Policy and Terms of Use.
Now on version 1.8 “Choose how you pay.” See the full update history →