Resonance: HRV Biofeedback launched on Android earlier this year. As of today it's on iPhone too. If you've been waiting to find your personal resonance breathing pace with the watch or chest strap you already own, this is the post that says you can.
What you get on iPhone
It's the same app, not a cut-down port. The iPhone version runs the same measurement engine as Android:
- The 12-minute assessment. A three-phase ASSESS → REFINE → HOLD protocol tests candidate breathing rates against your live heart-rate data and converges on the pace that is yours, rather than handing you a generic "6 breaths per minute."
- Live six-criteria coherence. All six Shaffer & Meehan (2020) criteria — peak power, single-peak dominance, LF concentration, peak height, SDNN, RMSSD — on screen during every session, so you can see the signal rather than trust a single score. Here's what each one means.
- Sensor-free daily practice. You need a heart-rate sensor to find your pace and for live biofeedback. Once your pace is stored, everyday sessions run at it with no hardware at all.
- Private by design. Your heart-rate data stays on your device. No account, no cloud, no sign-up.
- Eight languages. English, German, Spanish, French, Japanese, Italian, and Simplified and Traditional Chinese.
The full resonance assessment and unlimited practice are free. Resonance Pro adds the adaptive pacer, full breath history, the complete resonance score, sound packs, and the breathing exercises library, as a monthly or annual subscription or a one-time lifetime purchase. Prices are shown in the App Store at checkout for your region.
Pairing a sensor on iPhone
The app reads heart rate over standard Bluetooth, so anything that broadcasts the Bluetooth Heart Rate Profile works: chest straps like the Polar H10 or Garmin HRM-Pro, optical arm bands, and Garmin, Polar, Samsung, and Fitbit watches once heart-rate broadcast is switched on in the watch's own settings.
Apple Watch is the exception worth knowing about: it doesn't broadcast heart rate by default, so it needs a bridge app. Our device connection guide covers every device type, including that one, step by step.
Why it took this long
Bluetooth heart-rate handling is the part of this app that can't be faked or simulated. Getting it right on iOS meant testing against a real iPhone and real sensors rather than trusting a simulator, and the engine itself, the spectral analysis and the coherence scoring, runs on-device exactly as it does on Android. We'd rather ship late with the same measurement behind it than early with a different one.
What comes next
More languages are already in the app, and we're continuing to work on the breathing exercises library and on making the session data easier to read. If something doesn't work on your iPhone or your sensor, write to support@heartresonance.app — those reports shape what we fix first. And if you'd like to hear about new features and posts as they land, the subscribe form on the blog page is the place.
If the app is useful to you, a review on the App Store helps other people find it.
Related reading
- Why there's no universal "6 breaths per minute" — the reason the assessment exists
- How it works — the full protocol
- How to connect your heart rate monitor — every device type
- The free browser pacer — try slow breathing without installing anything