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Enter 1–120 years.
years
Use standing height; unit changes convert the value in place.
This is an optional model input, not an identity assessment.
Enter a resting value from 25–180 beats per minute.
bpm
{{ formatNumber(exhale_bias_percent, 0) }}%
Use −40% to 40%; zero is neutral.
Zero seconds keeps continuous breathing. Avoid forced holds.
top s bottom s
Use standardized values from −3 to 3; zero means no proxy adjustment.
vagal z fitness z
{{ formatNumber(width_bpm_add, 2) }} bpm
Zero keeps the base model width.
Off preserves full canonical timing; on rounds phase cues only.
{{ round_durations ? 'Enabled' : 'Disabled' }}
{{ round_durations ? 'Rounded to 0.1 s' : 'Full timing precision' }}
Choose one or two decimal places.
TrialRateCycleInhaleExhaleWhy test itCopy
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Slow breathing changes the timing relationship among respiration, heart rate, and blood pressure. Heart rate commonly rises during inhalation and falls during exhalation, a pattern called respiratory sinus arrhythmia. At certain slow rates, that breathing-linked rhythm can reinforce the baroreflex, the feedback system that helps regulate blood pressure.

Heart rate variability (HRV) resonance frequency is the breathing rate at which these cardiovascular oscillations respond most strongly for an individual. Six breaths per minute, one 10-second cycle, is a familiar starting point because it corresponds to 0.1 Hz. It is not a universal personal resonance frequency.

Term Practical meaning Important limit
Breaths per minute Complete inhale-to-exhale cycles in 60 seconds A lower number creates a longer cycle and may feel harder, not calmer
Resonance frequency The rate that produces the strongest coordinated physiological response It is normally assessed across several paced trials with recorded signals
Starting pace A candidate rate for comfortable exploration It is not a measured resonance result
Trial window Nearby rates worth comparing around a starting estimate The displayed curve is modeled, not recorded HRV response

A formal adult assessment commonly compares several breathing rates while monitoring respiration and heart activity. The result depends on signal quality, posture, breathing effort, comfort, and the criteria used to compare trials. A rate that maximizes one HRV measure may not maximize every other measure, which is why comfort and repeated physiological evidence matter.

Forcing a very slow or deep breath can cause air hunger, dizziness, tingling, or distress. Longer exhalation may feel comfortable for some people, but deliberate holds and large timing changes add effort and can make a paced rhythm less useful. Slow breathing should remain gentle; a smaller breath or a nearby faster rate is preferable to straining for a target.

A profile-based estimate can organize a first set of rates to try, but age, height, sex input, resting heart rate, or proxy scores cannot replace ECG or pulse-wave data plus respiration monitoring. Treat the estimate as a starting hypothesis and the body’s response as a reason to slow down, adjust, or stop.

How to Use This Tool:

Enter a calm resting profile, keep optional adjustments neutral unless they have a clear basis, and compare nearby rates without forcing the breath.

  1. Enter Age, standing Height, the optional Sex input, and a Resting heart rate measured while calm. A recent exercise or stress reading can shift the estimate.
  2. Leave the advanced proxy scores and Trial-window add-on at zero unless comparable standardized values or a wider comparison range are genuinely needed.
  3. Set Exhale bias and optional Breath holds only for a comfortable pacing cue. If the holds leave too little time for inhaling and exhaling at the fastest trial rate, the result is withheld until they are reduced.
  4. Read the estimated center, cycle duration, trial window, and warnings. Use Trial ladder to compare the center with nearby slower and faster rates.
  5. Stop if breathing causes dizziness, tingling, faintness, pain, or distress. A measured resonance assessment requires physiological recording and trained interpretation; do not label the estimate as a diagnosis or treatment setting.

Interpreting Results:

Estimated starting pace is the center of a repo-authored heuristic, rounded to 0.01 breath per minute before cycle timing is calculated. Trial window shows nearby comparison rates. Neither value reports a measured HRV peak.

  • Common starting band means the center is from 4.8 through 6.6 breaths per minute. Below 4.8 is labeled slower; above 6.6 is labeled faster.
  • Warnings appear for age below 10 or above 90, height below 100 cm or above 220 cm, resting heart rate below 40 or above 90 bpm, an exhale-bias magnitude above 35%, or a center outside 4.5 through 7.5 breaths per minute.
  • Response window is a normalized model curve. It cannot show HRV amplitude, breathing-heart synchrony, artifacts, or a personal resonance peak.

Technical Details:

The result is a deterministic, repo-authored starting heuristic rather than a published clinical formula. The cited HRV literature supports comparing instrumented breathing trials and the limits of a fixed rate; it is not the authority for the profile coefficients below.

Formula Core:

Height is first converted to centimeters. The raw center combines a 5.5-breath-per-minute base with bounded age, height, sex-input, resting-heart-rate, vagal-proxy, and fitness-proxy adjustments. The final center is clamped to 4 through 8 and rounded to two decimal places.

Craw = 5.5+A+H+S+R−0.12V−0.08F C = round to 0.01(clamp(4,8,Craw))
Symbol Input Exact adjustment
A Age +0.25 through age 20; +0.10 from 21 to 35; 0 from 36 to 50; −0.15 from 51 to 65; −0.30 from 66 to 80; −0.45 above 80
H Height in centimeters clamp(−0.4, 0.4, −0.4 × (height − 170) / 100)
S Sex input 0 male; +0.08 female; +0.04 prefer not to say
R Resting heart rate clamp(−0.5, 0.5, ((heart rate − 60) / 40) × 0.35)
V, F Optional standardized proxies Subtract 0.12 per vagal-proxy unit and 0.08 per fitness-proxy unit

The center rate determines the full cycle. Holds are subtracted before the remaining seconds are split between inhale and exhale.

tcycle = 60C tavailable = tcycle−ttop hold−tbottom hold fexhale = 0.5+clamp(0, 1, bias / 100)2

Positive exhale bias allocates more of the available time to exhalation. In the current calculation, negative bias values are treated like zero for the phase split, so they do not lengthen inhalation. Optional phase rounding changes the displayed inhale, exhale, and hold cues to 0.1 second but does not change the center rate or full-precision cycle.

The trial-window width starts at 0.35 breath per minute. Proxy values scale that width, the optional add-on widens it, and the result is clamped from 0.15 through 0.8. Window edges are the center minus or plus the width, each clamped to 3 through 9 breaths per minute.

K = clamp(0.7,1.4,1−0.08V−0.04F) W = clamp(0.15,0.8,0.35K+add-on)

A result is rejected when the two holds together leave less than 0.2 second for inhale and exhale at the fastest probe, which is the center plus 0.5 breath per minute clamped to 3 through 9.

Responsible Use Note:

This estimate is informational and is not a medical device, diagnosis, or treatment plan. It does not read heartbeats, respiration, blood pressure, or sensor quality. Anyone with a condition that may be affected by controlled breathing should seek appropriate clinical guidance before paced-breathing practice.

Keep breathing quiet and comfortable. Stop for dizziness, tingling, faintness, chest pain, unusual shortness of breath, or distress. Do not force deep breaths or holds to match a number.

Worked Examples:

Neutral adult profile

Age 35, height 170 cm, prefer not to say, resting heart rate 60 bpm, and neutral proxy values produce a 5.64-breath-per-minute center. The cycle is about 10.64 seconds, split evenly into about 5.32 seconds in and 5.32 seconds out, with a 5.29 to 5.99 trial window.

Holds leave no usable breath

If the combined top and bottom holds approach the fastest trial’s entire cycle, no pacing result is shown. Reduce or remove the holds until every trial leaves at least 0.2 second for inhaling and exhaling, then favor comfort over the displayed timing.

References: