PreciseBreath: HRV Biofeedback

At one specific breathing pace, your heart and lungs lock into sync. Researchers call it your resonant frequency. Many people find breathing at this rate calming and centering. Precise Breath analyzes your heart rate variability (HRV) to find yours. Premium features require a Bluetooth chest strap heart rate monitor; a free breathing timer mode works without any sensor. Most people fall somewhere between 4.5 and 6 breaths per minute, but the rate varies by individual. Being off by even one breath per minute substantially reduces the effect. Most breathing apps guide everyone at the same rate. Precise Breath measures yours. HOW IT WORKS The clinical approach tests several breathing rates in one sitting. Precise Breath builds on this — each session adds data, and the app narrows in on the rate that works best for you. Connect a Bluetooth chest strap heart rate monitor (Polar H10 recommended). The app measures how strongly your heart rhythm responds to each breathing rate and how well your breathing and heart rate stay in sync. After each block, the app scores your response and uses it to guide you toward your optimal rate. WHAT IT TRAINS Resonant frequency breathing activates the vagus nerve through the baroreflex — your heart-breathing feedback loop. Regular practice builds stress resilience and supports autonomic balance. Heart rate variability is the clinical measure of this response; higher HRV correlates with better stress recovery and cardiovascular health. SENSOR REQUIREMENT Measure and Calibrate modes require a Bluetooth chest strap heart rate monitor. Customize mode works without any sensor. Chest strap sensors provide the precision needed for meaningful HRV analysis. The Polar H10 (~$100 at polar.com) is recommended; any standard BLE chest strap works. Confirmed compatible: Polar H10, Garmin HRM Dual. FREE FEATURES • Customize — animated breath guide at any rate from 4.0 to 7.0 BPM, no sensor required • Adjustable inhale/exhale ratio (1:1, 2:3, 1:2) • Optional practice reminders (morning and evening) • Home screen widget — start a session without opening the app • Audio and haptics keep going when your screen locks or you switch apps • Haptic breath cues and bells audio PREMIUM FEATURES (one-time purchase) • Resonate — breathe at your personal resonant frequency, guided by your HRV history • Measure — finds your optimal rate across sessions by testing nearby rates and tracking which produce the strongest response. When your data supports it, the app adjusts your target based on your current resting heart rate • Calibrate — single-session test across 5 target rates to establish your baseline • HRV Analysis — scored for how strongly your heart responds and how well your breathing and heart rate stay in sync • Response Curve — visualize your personalized HRV response across breathing rates • Session History — full log with HRV scores, breathing rates, and trends • Progress Dashboard — monthly practice calendar and streak tracking • CSV Export — export your session data for personal analysis • Puff, Ocean, and Tone audio — procedural soundscapes that breathe with you YOUR PRIVACY All data stays on your device. No accounts. No analytics. No cloud sync. No advertising. You can export, back up, or delete your data at any time. Enable Private Mode to practice without storing anything, or use Delete All My Data to wipe everything at once. MEDICAL DISCLAIMER Precise Breath is a wellness tool for breathing practice. It is not a medical device and is not intended to diagnose, treat, or monitor any medical condition. If you have health concerns, consult a healthcare professional before beginning a breathing practice. REQUIREMENTS • Android 11 or later (API 30+) • Bluetooth Low Energy support • BLE chest strap heart rate monitor (for Measure/Calibrate modes). Confirmed compatible: Polar H10 (recommended), Garmin HRM Dual.