Free to download · Pro is a one-time purchase · No account
Winter-first
No tanning, ever
Your data stays on your iPhone
10 languages
9:41
London
Next best light
7:10–7:50
Until 7:50 · about 40 min
Your best light today
This is the sun engine from the app, running in your browser. Pick a place, when you wake up and the sky, and Soltide finds your window.
7:10–7:50
Estimates for open ground, not measurements; what reaches your eyes is usually lower. The app uses your own location and the live hourly forecast, and keeps the answer up to date through the day. Never look directly at the sun.
What is sunmaxxing?
The healthy version of the trend
Circadian sunmaxxing is the habit of getting outside within about an hour of waking, so natural daylight reaches your eyes. Soltide is built around the healthy version of the trend.
It’s about your eyes
Daylight reaching your eyes is the main signal that sets your body clock — helping you feel awake by day and sleepy at night.
Outdoors beats indoors
Even on an overcast day, outdoor light is usually 1,000 lux or more — several times brighter than a well-lit room (100–500 lux).
The first hours count most
Morning light matters most for your body clock. Later daylight may still help energy and mood — on grey winter days a lunch walk can be a good option.
Light, not a tan
Your skin doesn’t need UV for any of this. Soltide never sets tanning goals and shows you when to protect your skin.
How bright is it? Typical light levels, in lux
Well-lit room100–500
Overcast day, outdoors1,000+
Clear day, outdoors10,000–100,000+
Winter-first
Built for the dark months
Most sun apps are made for summer: UV, tanning, vitamin D. Soltide is made for the months when daylight is short, the mornings are dark and a grey sky hides the light — which is exactly when it’s hardest to get.
Weather-aware
Soltide lowers its light estimate for cloud and rain, hour by hour, and moves your window to where the light is.
Season-aware
Shrinking days, the clock change, the shortest day — and then the light returning, minute by minute.
Honest about vitamin D
When the sun is too low for your skin to make much vitamin D, Soltide says so plainly and points you to a doctor or pharmacist — not to more sun.
Free, every day
One clear answer, every morning
Next best light
The top of Today is one time window — like 7:10–7:50 — with how long to stay out and how bright it will be.
Sun arc and sky by hour
The sun’s path through your day, shaded by the hourly forecast, with your best light and the current time marked.
Your day, planned
Best light, the brightest half hour, sunset and when to dim the lights, in one timeline.
UV and safety, always free
When UV reaches 3, Soltide shows when to protect your skin. Safety information is never behind a paywall.
The season at a glance
Daylight for the days ahead, the next clock change, and the countdown to the shortest day.
Widgets and Apple Watch
Your next best light on the Home Screen, the Lock Screen and your wrist, with complications and a session timer.
A nudge when the light is right
One nudge a day, 15 minutes before your best light. Never more than two a day.
A gentle log
Start a session, or add 10 or 20 minutes with a tap. A 7-day chart and a streak, without the guilt.
Soltide Pro
The coach that works in the background
One purchase. Yours for good.
Sun-break alerts
A nudge when a sunny spell is forecast in your free time — the light grey days hide.
Plans around your day
Soltide sees when you’re busy in Calendar and finds the light between meetings.
Travel and clock changes
A day-by-day light plan for new time zones, and a gentle 3-day shift before the clocks change.
Insights
Your light over weeks and months, next to your sleep from Apple Health.
Automatic tracking
Apple Watch fills in your light log, and timed sessions are saved to Apple Health.
Plan two weeks ahead
Free shows the next 3 days. Pro plans your best light up to 14 days out.
Today’s best light, UV and safety information, widgets and the session timer are always free.
One-time purchase — no subscription. Shared with your family through Family Sharing.
How Soltide works
Honest science, plainly said
The sun’s path
Soltide calculates where the sun is for your place and date, accurate to about two minutes for sunrise and sunset.
Estimated light
From the sun’s height, Soltide estimates outdoor light in lux, then lowers it for cloud and rain using the hourly forecast. These are estimates, not measurements.
Your best light
Soltide looks for a time you can actually get out to reach a light goal of about 30 minutes of bright outdoor light. The 30-minute goal is a habit target Soltide chose, borrowed from bright-light research — not a clinical dose.
Light, not UV
Your body clock responds to visible light at the eyes; UV does nothing for it. When UV is 3 or more, seek shade, cover up, wear sunglasses and use SPF 30+ — sunscreen isn’t a reason to stay out longer. No tanning goals, ever.
Sources: sun position — low-precision algorithm checked against NOAA’s Solar Calculator. Light — Haurwitz clear-sky model. UV — WHO Global Solar UV Index guide (2002) and Madronich (2007). Light timing — Brown et al., PLOS Biology (2022). Vitamin D — NHS and SACN guidance.
Soltide offers general wellness information, not medical advice. Light levels are estimates. If you have health concerns, talk to a doctor.
Privacy
Your light stays yours
No account, no ads, no tracking. Soltide works out the sun on your iPhone.
Your log stays on your iPhone
Your light log, settings and places are kept on your iPhone. Health and Calendar are read on the device and never leave your devices.
Only an approximate area leaves
For the forecast, the app asks Apple Weather directly for an area about 10 km across — never your exact location. We run no servers for the app.
Nothing to sell
Soltide has no analytics, no advertising and no account. A one-time purchase pays for it.
Soltide is coming to the App Store for iPhone and Apple Watch this winter.
Is Soltide free?
Yes. Today’s best light, the sun arc, UV and all safety information, widgets, the Apple Watch app and the session timer are free. Soltide Pro is a one-time purchase — no subscription — that adds sun-break alerts, calendar-aware plans, travel and clock-change coaching, Insights, automatic Apple Watch tracking and 14-day planning.
Do I need an Apple Watch?
No. Start a session or add minutes with a tap on your iPhone. With an Apple Watch, the Soltide watch app shows your next best light and a session timer, and with Pro your Time in Daylight from Apple Health fills in your log automatically.
Does it work on cloudy days and in winter?
That’s what it’s made for. Even on an overcast day, outdoor light is usually 1,000 lux or more — several times brighter than a well-lit room. Soltide uses the hourly forecast to find the brightest time you can get out, and tells you plainly when light is scarce.
Will Soltide help me tan or get vitamin D?
Soltide is about light reaching your eyes, not UV on your skin. It never sets tanning goals, and it shows you when UV is high enough to protect your skin. For vitamin D it says honestly when the sun is too low for your skin to make much, and points you to a doctor or pharmacist rather than to more sun.
Is Soltide medical advice?
No. Soltide offers general wellness information, not medical advice. Light levels are estimates. If you have health concerns, talk to a doctor — especially if you have bipolar disorder, an eye or retinal condition, take medicines that make you sensitive to light, or have had skin cancer.
What does Soltide know about me?
Very little. There’s no account. Your light log and settings stay on your iPhone, and Health and Calendar are read on the device only. For the forecast, the app asks Apple Weather directly for an approximate area — never your exact location. We run no servers for the app and receive none of your data. See the privacy policy.
Is there an Android version?
Not yet. Soltide is for iPhone and Apple Watch first.
The days are getting shorter. Catch the light you have.
