HRV-Tracker

HRV Tracker — 100% Free SDNN, RMSSD, all-day Stress, Recovery score and Energy from your Apple Watch. Free, no ads, no subscription.

HRV Tracker — native iPhone & Apple Watch app that turns heart rate variability into actionable health insights.

OVERVIEW HRV Tracker reads your HRV from Apple Health and presents it through clean, scientific visualizations: an all-day stress curve, an Energy (Body Resources) reserve, a nightly Sleep Score, and a personalized Recovery score. It tracks both SDNN (Apple's standard HRV metric) and RMSSD (from raw beat-to-beat intervals) for a complete view of autonomic nervous system activity.

iOS APP • Five views: Home, SDNN, RMSSD, Stress, and Energy • Dual HRV metrics (SDNN + RMSSD) side by side • All-day Stress curve combining heart rate and HRV, with sleep and workouts overlaid • All-day Energy reserve that drains under stress and recharges with rest and sleep • Nightly Sleep Score blending duration, continuity and HRV-based restfulness • Personalized Recovery score from your 7-day baseline • Age-adjusted zones using research-backed thresholds • Daily, weekly, monthly and yearly trends with interactive charts

APPLE WATCH APP • Native app with circular Recovery and Stress gauges • Inline SDNN and RMSSD values at a glance • Statistical Z-score analysis vs your personal 7-day baseline • Dedicated SDNN, RMSSD and Stress chart complications with live data • RMSSD computed in real time from raw RR intervals (heartbeat series) • Background processing with optimized battery usage • Supports Graphic Corner, Circular, Bezel, Rectangular and Extra Large

DATA REQUIREMENTS Important: This app delivers meaningful insights only when AFib History is enabled on your Apple Watch (Watch app › Heart › AFib History). It greatly increases beat-to-beat data collection, providing the rich dataset needed for accurate stress curves, energy tracking, statistics and personal baselines. Without it, measurements are too infrequent for reliable trends, stress, energy or recovery.

KEY FEATURES

All-Day Stress • Continuous 0–100 score computed at every heart-rate sample for a dense intraday curve • Two signals weighted 50/50: your RMSSD ranked against your history, and your heart-rate reserve • Smoothed trend showing how stress builds and fades through the day • Sleep shaded, workouts excluded, so it reflects genuine autonomic stress • Watch-off periods clearly greyed out

Energy — Body Resources • An all-day 0–100 reserve showing how much you have "in the tank" • Depletes with stress and effort, recharges during genuine calm and sleep • Sleep-stage aware: deep sleep restores most, REM least • Fully reproducible from Apple Health — no stored state, always consistent

Sleep Score • A 0–100 score for last night, on the Home card and a history screen • Blends duration (40%), continuity (30%) and restfulness (30%, from your overnight HRV) • Colour-banded poor/fair/good/excellent, with per-night history and averages

Dual HRV Metrics • SDNN: standard deviation of NN intervals from Apple Health • RMSSD: root mean square of successive differences, from raw heartbeat series • Side-by-side on iPhone and Apple Watch

Smart Recovery Scoring • One unified Recovery score across iPhone and Apple Watch • Based on your RMSSD trend vs a personal 7-day rolling baseline • Filtered baselines that exclude statistical outliers • Adaptive algorithm that improves as it learns your patterns

Visualization • Daily, weekly, monthly and yearly trends with interactive charts • Filtered baselines and personal historical ranges • Color-coded zones inspired by heart-rate training systems

All HRV data stays on-device and integrates with Apple Health. Nothing is sent to external servers — complete privacy of your health information.

For health-conscious individuals, athletes and wellness enthusiasts seeking evidence-based recovery and stress insights through HRV. Requires Apple Watch with AFib History enabled for optimal functionality.