Personalized, not population
14-Day Rolling Baseline
Tuning compares each day against your personal 14-day rolling window — not fixed population averages. The baseline adapts to travel, seasons and lifestyle.
Now available on the App Store
Understand your nervous system. Recover with real data.
Tuning converts complex Apple Health SDNN data into clear daily readiness scores, root causes, and actionable recovery steps.
- Real Apple Health samples
- SDNN
- Real Apple Health samples
- Personal rolling baseline
- 14-day
- Personal rolling baseline
- On-device processing
- 100%
- On-device processing
SDNN samples from your Apple Watch drive every chart — nothing is simulated.
SDNN · 24h Ready 82
Why Tuning is different
Three pillars, one honest signal
Most recovery apps show you simulated curves. Tuning shows you the truth from your own body.
Zero fake simulations
100% Real SDNN Data
We never simulate recovery curves. Progress is displayed only when Apple Health records new real SDNN samples. No manufactured graphs, ever.
Status → Cause → Action → Verify
Action System, Not Just a Dashboard
Four questions answered daily: What is my status today? What caused it? What should I do? Did it work? Every insight maps to a concrete action.
How It Works
Your baseline gets personal, fast
Within two weeks, Tuning builds a baseline that knows your body — and keeps adapting after that.
- 1
Day 3
Initial Assessment
After 3 valid measurement days you get a first read on your nervous system — early signals, not a verdict.
- 2
Day 7
Formal Baseline
Your personal baseline is formally established from 7 valid days of your own SDNN samples.
- 3
Day 14+
Continuous Dynamic Adaptation
A 14-day sliding window keeps re-baselining — adapting to travel, seasons, training load and lifestyle changes.
Pricing
Start free. Upgrade when you want more depth.
Every feature — free or Pro — processes your health data 100% on-device.
Tuning Free
Build your personal baseline and build the daily check-in habit.
$0 / Monthly
- Personal baseline built from your SDNN data
- Daily readiness score
- Basic guided breathing protocols
- 14-day rolling baseline
- 100% on-device privacy
Tuning Pro
Deep insight and structured recovery — for when you want the full picture.
$1.99 / month
$5.99 / year -75%
- Everything in Free
- 30/90-day trend analysis
- Deep AI stress insights & root cause attribution
- Weekly recovery reports
- Full guided breathing protocol library
Pro is $1.99/month or $5.99/year. Cancel anytime — no hidden fees. Subscription processes data locally only.
Science & FAQ
Honest answers to the questions that matter
We explain the science the way we build the app — transparently.
Why SDNN instead of population standards?
SDNN is the primary time-domain measure of heart rate variability that research links to stress load and recovery capacity. But a “normal” range differs enormously between a 25-year-old athlete and a 60-year-old office worker. Tuning anchors every reading to your own 14-day baseline, so a value that looks “average” in a population table can still signal a meaningful shift for you.
How does the 14-day rolling baseline work?
Tuning only ever stores your own SDNN samples. Day 3 gives an initial assessment, Day 7 establishes a formal baseline, and from Day 14 onward a sliding 14-day window continuously re-baselines. Your readiness is the distance between today’s samples and your personal window — never a fixed population norm.
Does Tuning simulate workout recovery?
No — this is our core principle. We never fabricate or extrapolate recovery curves. If Apple Health records a new SDNN sample, the chart moves; if it doesn’t, nothing is drawn. What you see is always the real signal from your watch.
Is my health data secure and private?
Yes. 100% of HealthKit data processing happens on-device. Tuning never uploads, stores, or shares your health data — there is no account database of your readings, and nothing ever leaves your iPhone.