Most breathing apps give you someone else's breathing rate. Resonance: HRV Biofeedback finds yours.

Your resonance frequency — the breathing pace that maximizes your heart rate variability (HRV) — is unique to you. It's usually 4.5 to 6.5 breaths per minute, but the exact rate is personal. Breathing there triggers respiratory sinus arrhythmia (RSA), strengthens vagal tone, and builds stress resilience. A generic pace like "6 breaths per minute" misses it for most people.

Resonance uses live HRV biofeedback to measure your actual resonance frequency, then trains you at that exact pace.

START WITH THE WATCH YOU ALREADY OWN

Turn on heart-rate broadcast on your Garmin, Polar, Samsung, or Fitbit watch and you're ready — no extra hardware to buy. Any Bluetooth chest strap or arm band works too (Polar H10, Garmin HRM-Pro, Wahoo TICKR, and more).

You only need a sensor twice: for the 12-minute assessment that finds your frequency, and whenever you want live coherence biofeedback. Every daily practice session after that runs at your stored pace with no sensor at all.

FIND YOUR FREQUENCY IN ABOUT 12 MINUTES

A three-phase protocol — ASSESS, REFINE, HOLD — scores candidate breathing rates against your live HRV using the published Shaffer et al. (2020) six-criteria coherence model, then locks in your personal resonance frequency and refines it each session.

LIVE HRV BIOFEEDBACK, NOT A BLACK BOX

• Real-time heart-rate trace and frequency spectrum during every session
• All six Shaffer coherence criteria live — peak LF power, single-peak dominance, LF concentration, peak height, SDNN, RMSSD
• Watch your heart rate turn into a smooth, sine-like wave as heart coherence builds

TRACK REAL IMPROVEMENT

• Session Quality Score (0–100) after every session — time in coherence, RSA amplitude, and consistency, scored separately
• Full session history with HRV trend charts for coherence, resonance, RMSSD, breathing pace, and heart rate
• Shareable session cards with your actual heart-rate trace

BUILT FOR DAILY PRACTICE

• A calm breath pacer with visual, audio, and haptic cues for eyes-closed sessions
• 10 sound packs and a breathing exercises library with multiple session modes
• Custom inhale/exhale ratio and practice reminders

PRIVATE BY DESIGN

Your heart-rate data never leaves your device. No account, no cloud, no sign-up. Everything works offline.

FREE TO START

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 exercises library — available monthly, annually, or as a one-time lifetime purchase.

THE SCIENCE

Built on 30+ years of peer-reviewed HRV biofeedback research. The engine uses Lomb-Scargle spectral analysis, the HeartMath coherence ratio, and the full Shaffer six-criteria model — the same methods used in clinical biofeedback, computed on-device.

Resonance: HRV Biofeedback is a wellness tool, not a medical device; it does not diagnose or treat any condition.

References:
Task Force (1996)
Lehrer et al. (2000)
Shaffer & Ginsberg (2017)
Shaffer et al. (2020)

COMPATIBLE DEVICES

Any Bluetooth 4.0+ heart-rate sensor using the standard Heart Rate Service — smartwatches, chest straps, and arm bands. Tested with Garmin HRM-Pro, Polar H10, Wahoo TICKR, and Garmin, Polar, Samsung, and Amazfit watches with heart-rate broadcast on.

WHO IT'S FOR

Anyone training heart coherence and resonance frequency breathing — for stress, anxiety, focus, sleep, and vagal tone. First-timers who want a guided daily practice that works, athletes using breathwork to recover and downregulate, and researchers who want live spectral analysis, RMSSD, SDNN, and raw R-R export. No prior HRV knowledge needed.

Resonance frequency breathing. HRV biofeedback. Heart coherence training. Vagus nerve activation. Measured, not guessed.