Track your period. Full stop.
A calendar, a guess, a pink flower. They log the days and hand you nothing you can actually train on.
Cycle tracking, meet the barbell
Lift with your cycle,
Lift with your cycle,
not against it.
Ferrabelle is the Android app that knows your cycle and your barbell. It turns what you log into a daily training call and, with Pro, a 7-day look ahead, so you can plan the heavy lifts around how you actually feel. And all of it stays on your phone.
Coming to Google Play: free, with an optional Pro unlock for $9.99 once. Pro adds the 7-day forecast, training blocks, the AI assistant and the printable report. No subscription, no account, no ads.
Everything stays on your phone. With the AI assistant off, it never goes online.
Proof, not promises
Accuracy you can check.
Most apps say "smart predictions" and leave it there. We replayed Ferrabelle's real prediction engine against a public research dataset of 1,665 cycles from 159 women: 3,282 scored predictions, each made before the period arrived. Median miss: one day. Like for like, it beats the calendar method by 12% (1.82 vs 2.08 days mean error).
1 day median prediction error
76% within 2 days
3,282 real predictions scored
Grounded in published research on 600,000+ cycles, validated on data our engine was never tuned on, and updated whenever the engine changes. Read exactly how we measure it →
Ferrabelle is not a medical device and is not a contraceptive. Predictions can be wrong.
Why we exist
Every other app tracks your period.
Every other app tracks your period.
Ferrabelle trains with it.
Your cycle is not a problem to manage. It is a performance signal you have never been able to use. Until now.
Knows your lifts too.
Log the barbell alongside the cycle. Ferrabelle puts the two side by side so you can see your own patterns.
Plans around how you feel.
A daily training call from your cycle phase and what you log: sleep, stress, recovery, calories and recent training, and, with Pro, a 7-day look ahead. Research on cycle phases and strength is mixed, so together your own logs count for more than your cycle phase.
How it works
Three taps in. A training edge out.
Log your cycle and your lifts
A few taps a day. Period, sleep, how the session felt, what you moved. Or bring your history in from Health Connect, Flo or Clue. No spreadsheets, no judgement.
Ferrabelle learns YOUR body
The engine calibrates to you, not a textbook average, right on your phone. Every cycle sharpens the forecast for the next one.
Get your Fe Score and training forecast
One readiness number every morning, free. With Pro, a 7-day look ahead at your training calls.
The Fe Score
One number answers one question. Push, or rest?
Every morning Ferrabelle fuses where you are in your cycle with your sleep, your stress, and how well you recovered, then hands you a single readiness score from 0 to 100. No graphs to decode at 6am. Just the call.
- Cycle phase
- Sleep
- Stress
- Recovery
Ferrabelle is a training and wellness companion, not a medical device and not a contraceptive. It does not provide medical advice, and predictions should not be used to prevent or achieve pregnancy.
82 Fe Score
You are primed to push today.
Training forecast
See your next 7 days of training calls.
The forecast starts from your predicted cycle phases: often stronger in the first half of your cycle, lighter during your period and in the second half. Research on cycle phases and strength is mixed, so treat it as a guide and go by how you feel. The 7-day forecast is part of Ferrabelle Pro.
Rest Mon
Easy Tue
Moderate Wed
Go Thu
Go Fri
Moderate Sat
Easy Sun
Rest Easy Moderate Go
Side by side
Pick the app that can prove it.
The others are good at what they do. None of them were built for the woman under the bar.
| Feature | Ferrabelle | Flo | Clue | Wild.AI | WHOOP / Oura |
|---|---|---|---|---|---|
| Set-by-set lifting log with PR-by-phase | ✓ | No | No | No | No |
| Readiness score that shows its math | ✓ | No | No | No | black box |
| Publishes a replayable accuracy test (public dataset and method) | ✓ | No | No | No | No |
| Works without buying hardware | ✓ | ✓ | ✓ | ✓ | No |
| Price | Free, Pro $9.99 once | ~$50/yr | ~$40/yr | ~$64/yr | $199+/yr or a $300+ ring + $5.99/mo |
Based on each product’s published features and pricing, as far as we could find in mid-2026. “No” means not offered or not published. WHOOP and Oura are excellent hardware; they solve a different problem.
Your data, locked and yours.
Privacy, front and center
Your body’s data stays yours.
Tracking your cycle takes trust. In a post-Roe world that trust is not a nice-to-have, it is the whole point. So Ferrabelle keeps your data where it belongs: with you.
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It lives on your phone
No account, no sign-in, no Ferrabelle servers. Your cycle, your lifts and your body data live on your phone, and backups go only where you choose.
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Offline by default
With the AI assistant and pressure tracking off, which is how Ferrabelle starts, the app makes no internet connections at all. We measured it: zero bytes leave the phone. The app’s privacy meter lets you check it yourself.
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Backups only you can open
Save an encrypted backup wherever you like, such as Google Drive. It is locked with a passphrase that only you know.
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AI only if you turn it on
You pick where it runs, from your phone’s own AI to a server you control. You see every question before it goes, and raw Health Connect values are never included.
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Nothing for us to sell
We never receive your health data, so we cannot sell it, share it or lose it in a breach. No ads, and no analytics or trackers of our own.
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Export or erase it anytime
Take a full export with you, or delete everything on the phone from Settings in a few taps.
Read the Privacy Policy, the Consumer Health Data Privacy Policy, how we measure accuracy, and how to delete your data.
Why this exists
Built for one lifter first.
Ferrabelle started after an argument. Chris told his wife, Steffany, that he would build an app just for her, so he could understand her better. She lifts, and every cycle app she had tried treated her training like it did not exist.
Today it is the only cycle app she uses, and she says it is the most accurate she has ever had. Every feature is here because she actually used it.
From the articles
Notes on lifting and your cycle.
Plain-language reads on training through each phase, tracking, and keeping your data on your phone.
Lifting through your cycle: what the research actually says
The biggest reviews on strength training and the menstrual cycle find trivial to small effects and low-quality evidence. Here is the honest scorecard.
Read the articleHow Ferrabelle predicts your next period (and how I check it)
Where the starting assumptions come from, how the app learns your cycle, and the published test: a 1-day median error on a public dataset, weak spots included.
Read the articleWhy your cycle data stays on your phone
Why I built Ferrabelle with no account and no server, what local-only means in practice, and how you can check it yourself on your own phone.
Read the article
Coming to Google Play
Help us open the doors.
Ferrabelle for Android will be free, with an optional Pro unlock for $9.99, once. Before Google lets a new app go live, at least 12 people have to test it for 14 days in a row. Be one of them (testers try Pro at no cost), or get one email when it is out.