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About this tool
Track your personal HRV baseline and how far each morning deviates from it.
The HRV Readiness Trend Tracker compares each day's heart-rate variability reading against a rolling baseline — the mean of the preceding readings, 7 by default — and reports the percentage deviation, flagging any day that sits more than your chosen threshold (±15% by default) away from that baseline. Paste your own readings as date | value, and you get a per-day table of HRV, prior baseline, deviation and whether it crossed the band. It is a trend aid for people already logging HRV from a chest strap or wearable, not a readiness score and not a medical assessment.
Open HRV Readiness Trend Tracker on AltFTool — it loads instantly in your browser.
Paste your readings into Daily HRV readings, one per line as date | value — the loaded example runs 2026-07-17 | 55 through seven mornings.
Set Rolling baseline window, which defaults to 7 readings and will not go below 3, and Deviation flag (%), which starts at 15.
The result line gives the latest baseline deviation as a percentage, and the table lists Date, HRV, Prior baseline, Deviation and a Context flag of 'Review context' or 'Within entered band' for every day; Download saves it as hrv-readiness-trend-tracker.txt.
The reference is the mean of your own preceding readings, so nothing is normalised against population data or a hidden scoring model.
Set a shorter window to react faster or a longer one to smooth noise, and set the flag percentage to whatever your own day-to-day spread justifies.
A day is only marked for review once at least three prior readings exist, so the first few entries do not generate meaningless alerts.
It is the plain average of the readings immediately before the current one, up to the window size you set — 7 by default. The current day is excluded from its own baseline, so deviation = (today − baseline) ÷ baseline × 100. A reading of 48 against a prior mean of 57.8 gives roughly −17%.
The default is ±15%, which is a common starting band, but the right figure depends on how variable your own readings are. If most normal days already exceed 15%, widen it until only genuinely unusual days trip the flag; if nothing ever flags, tighten it.
Because HRV depends on the metric, the measurement window and the conditions. RMSSD, SDNN and an app's own 0-100 score are different quantities, and readings taken lying down on waking differ from ones taken overnight or seated. Only compare readings from the same device taken the same way — mixing sources makes the baseline meaningless.
It does not mean anything on its own. A dip can follow poor sleep, alcohol, illness, medication, stress, dehydration or simply a mistimed measurement, and this tool deliberately outputs 'review context' rather than a training instruction. It is informational only — if low readings persist or come with symptoms such as chest pain, breathlessness or an unusual resting heart rate, speak to a doctor.