Track your cycle
Log your periods and see predictions for your next period, ovulation day, and fertility window, so you always know what’s coming and can plan ahead.
Stay in tune with your menstrual cycle, privately.
Data stored locally and encrypted
Ad-free experience
No third-party tracking
Open source
What can you do with Bluma?
Symptoms and mood tracking
Track what's happening in your body and mind to identify patterns.
Cycle statistics
Get a full picture of your cycle and get a sense of what's normal for you.
Unlock app with biometric
Use your device's biometric authentication (e.g Face ID or fingerprint) to unlock the app.
Set cycle-related reminders
Get a heads-up so you’re always prepared.
Why you'll love Bluma?
Privacy‑first by design
Built from the ground up to store your data locally on your device.
On-device predictions
Predictions are computed on‑device from your cycle history, no cloud needed.
Open source
Bluma has nothing to hide, you can inspect the code on GitHub.
Crafted with purpose
I was concerned about how health data is handled by many period tracking apps. I tried local-first alternatives, but they felt clunky and lacked features I needed.
Privacy and a good experience shouldn't be a trade-off. So I built Bluma, designed to be a delight to use while keeping your data on your device.
Maribel Ferreira
Creator of Bluma
How Bluma calculates predictions
Next period prediction
Bluma predicts your next period by adding your average cycle length to the start date of your last period.
Cycle average length calculation
Bluma calculates your average cycle length using a weighted average of your last 6 cycles, a commonly used approach in cycle tracking.
Recent cycles have more influence on predictions than older ones. For example, most recent cycle: 100%, second most recent: 80%, third most recent: 60%, and so on.
More data, better accuracy
Track at least 3 cycles for basic predictions. After 6 cycles, predictions are more accurate.
IMPORTANT: Predictions are estimates based on your tracking history, not medical advice. See a healthcare provider if you have concerns.