Your body loses power without you knowing.
Most athletes train hard and recover poorly — not because of effort, but timing. Flux uses circadian science and peer-reviewed data to tell you exactly when and how much to drink, so you feel the difference from day one.
Athletes who feel the difference.
Drag to explore
“The timing reminders changed my races. Not bonking in hour three anymore.”
“Power output in the third hour finally stopped collapsing.”
“WOD performance was all over the place. Now I know why — and fix it daily.”
“60 seconds off my finish time. Pre-race hydration timing made the wall stations easier.”
“Transition hydration used to be guesswork. Now I have data.”
“You sweat in the pool without knowing it. Flux made that visible.”
“Mental sharpness in the third set. That’s where Flux makes the difference.”
“Recovery between sets improved noticeably. Hydration was the variable I ignored.”
“Sprint speed in the 80th minute. That’s what proper hydration timing gives you.”
“High altitude dehydration used to ruin day two. Not anymore.”
“Split times improved when hydration was optimized. Simple as that.”
“I track everything. Flux is the one tool that actually changed my numbers.”
Find your hydration score
6 questions. 60 seconds. See exactly where you lose performance — and what Flux fixes.
Where did you hear about Flux?
Calculate your exact hydration need
Based on body weight, training, environment and biological factors — the daily target a hydration app for athletes should give you, grounded in peer-reviewed circadian science.
Your parameters
All values can be adjusted later in the app.
Your daily target
3’275
ml per day
Drag the slider. See what happens.
This is what happens inside your body — based on peer-reviewed data from Sawka, Armstrong and Judelson.
Fully hydrated — optimal
Performance sport
Your body only shows dehydration signs after losing 1–2%. By then, the performance curve is already declining.
You are optimally hydrated. Keep it up.
See your circadian protocol. Live. Every day.
The hydration curve shows your cumulative intake against the optimal circadian protocol, built on the Huberman Lab timing work and Sawka’s hydration research — so you know at any moment whether you are ahead, on track, or falling behind.
Target protocol
Your personalised circadian curve — front-loaded in the morning, peak absorption in the afternoon, tapered before bed.
Your progress
Live cumulative intake, updated with every sip — logged by hand or through the Smartsip bottle.
Now
Your current position on the curve. The gap between the dots is how far you are from the protocol at this moment.
Hydration curve
Scientific protocol80%
On trackYour data stays in Switzerland.
Flux is built and operated in Switzerland. Your health data is stored exclusively on Swiss servers — subject to some of the strictest privacy laws in the world.
Swiss server infrastructure
No data leaves Switzerland.
nDSG / GDPR compliant
Swiss Federal Act on Data Protection.
Zero data selling
Your health data is never monetised.
Built in Zurich
A small team that takes your data seriously.
Connects to your ecosystem.
Flux works with the devices you already use. Not a WHOOP or Oura alternative but the hydration layer they leave out: it pulls activity data automatically to calculate your real need, with no manual input.
Apple Health
Sleep, workouts and activity
Garmin Connect
Training load and HRV
Whoop
Recovery and strain
Oura Ring
Sleep and readiness
Fitbit / Google Fit
Steps and activity
Simple. No free tier.
7-day free trial. Full access from day one. No degraded version — either you have Flux or you do not.
CHF9.99
- Circadian timing protocol
- Live Activity + Dynamic Island
- Performance impact scores
- Full analytics
- Daily science insights
- Custom notification style
CHF79.99
- Everything in Monthly
- Priority feature access
- Locked-in price guarantee
Your reminders, your tone.
Choose how Flux talks to you — from peer-reviewed to brutally honest.
“Peak absorption window open. Cortisol curve descending — optimal cellular uptake efficiency now.”
“You are 68% to your daily target. Champions do not quit in the third quarter.”
“Seriously? It is 2pm and you have had 800 ml. Your plants drink more. Go drink.”
“A gentle reminder: your body asked for water about an hour ago. Take a moment.”
Stop guessing. Start measuring.
A water tracker built for performance and longevity, not a reminder app. Full access from day one, no degraded free version. If Flux does not change how you perform in 7 days, cancel.
Download on the App Store →7-day free trial · No charge until day 8 · Cancel anytime
What athletes report back.