Suunto’s HRV feature compares your recent nights with your own usual range. The watch takes the readings at night, the Suunto app makes the comparison, and on the Suunto Run and Run 2 a Recovery widget folds HRV into a wider score. A separate feature, ZoneSense, reads HRV from a chest belt while you exercise.
Documentation checked: 22 October 2026. Suunto updates its watches and app often, so details can change.
What HRV number Suunto shows
Suunto’s July 2026 article on HRV and recovery, on its Asia-Pacific site, says of its watches: “The measurement uses a metric called RMSSD RMSSD Root mean square of successive differences: an HRV metric built from how much each heartbeat interval differs from the next, in milliseconds. It mainly reflects vagal activity. More about RMSSD (Root Mean Square of Successive Differences)” (Suunto, July 2026). RMSSD is the standard short-term measure of how much one beat-to-beat interval RR interval The time from one heartbeat to the next, measured in milliseconds between the R peaks of an ECG. HRV is calculated from a series of these intervals. More about RR interval differs from the next (Task Force, 1996).
The September 2026 version of the article on suunto.com words it more generally. Under the heading “RMSSD: the metric behind the number”, it says that for recovery tracking most sports watches “lean on nighttime readings and an indicator called RMSSD” (Suunto, September 2026). Both versions name RMSSD, and the July one says outright that Suunto’s own measurement uses it. Neither page says which part of the night the value covers or how the watch handles missed beats, so you cannot match it to another brand’s value.
When Suunto measures
Wear the watch to bed with sleep tracking on. In the user guides for the Race 2, Race 3S, Run and Run 2, HRV tracking is its own switch in the sleep settings, next to blood oxygen (Suunto user guides). The watch tracks sleep from its accelerometer, and Suunto says its sleep measurements are “based on movement only, so they are estimates that may not reflect your actual sleep habits” (Suunto user guide, Race 2). Suunto says the watch measures HRV “through the night” (Suunto, September 2026); it does not say whether the value covers the whole night or a shorter window.
Suunto’s two articles list overnight HRV on eight watches: the Vertical 2, Vertical, Race 2, Race S, Race, Run, Ocean and 9 Peak Pro (Suunto, July and September 2026). The user guides for two newer models, the Run 2 and Race 3S, describe the same HRV option (Suunto user guides, Run 2 and Race 3S).
Values appear soon after you start, but the comparison takes time. The normal range needs at least 14 measurements and the 7-day average at least 3 (Suunto, July 2026). The user guides give a rougher rule: track your sleep “at least three times a week over a longer period to establish your HRV range” (Suunto user guide, Race 2). How long until my HRV baseline is reliable compares these waits with other devices.
How the Suunto HRV status works
The app calls the comparison HRV status. Your normal range comes from 60 days of data, and your current 7-day average is set against it as a bar indicator in three colours (Suunto, July 2026):
- Green: “Good recovery, ready for training.”
- Yellow: “Recovering, moderate training load recommended.”
- Red: “Insufficient recovery, rest or reduced load needed.”
An average above the range can also count against you. If HRV rises “far above a certain standard deviation”, the bar may turn yellow or red, which Suunto says can mean the body is mounting a strong recovery response to accumulated stress (Suunto, July 2026). The September article calls a reading a little above usual “potentially strong recovery” and a very high one “an atypical response” to check against other signals before adding load (Suunto, September 2026).
How Suunto reads your nightly HRV
Made-up nights, Suunto’s published rules
- One night’s HRV
- Your normal range
- 7-day average
- Green: “good recovery, ready for training”
- Yellow: “recovering, moderate training load recommended”
- Red: “insufficient recovery, rest or reduced load needed”
- A little above the range: “potentially strong recovery”
A dot chart of 50 made-up nightly HRV values over 60 days; on 10 nights the watch was not worn. A shaded band marks the normal range, 44.3 to 54.7 ms. The last 7 days have 6 values, and their average, 42.2 ms, sits below the range, so the status gauge beside the chart points at yellow. From the bottom, the gauge runs red, yellow, green across the normal range, uncoloured a little above it, and yellow or red far above it.
Suunto does not publish how the range is calculated beyond the 60 days, how wide it is, or where yellow becomes red, so the figure draws those parts for illustration.
Because the status uses a 7-day average, one poor night moves it only a little, and a run of low nights can keep it low for a few days after you feel better. Suunto calls a temporary drop after a race or a hard session “a normal response”; the concern is HRV that “does not recover for several days or more” (Suunto, July 2026).
Where to find HRV on a Suunto
- On the watch. The Race, Race 2, Race 3S, Vertical 2 and 9 Peak Pro have a widget called Recovery, HRV (Heart Rate Variability) (Suunto user guides). On the Suunto Run and Run 2, the Recovery widget sits in the All Apps menu, and you can add it to your widget list (Suunto user guides, Run and Run 2).
- In the Suunto app. Sync after you wake up, then open the Training Zone section or the mini widget (Suunto, July and September 2026).
Where do I find HRV on my device has the same steps for other brands.
Recovery on the Suunto Run and Run 2
The Recovery widget on the Suunto Run and Run 2 shows a percentage for “how well your body has recovered since your last training or after an illness or a stressful period”, with a coloured scale below it. Suunto calculates it from “three main factors”: the average of your HRV over the last seven days, your tracked sleep over the last seven days, and Training Stress Balance (TSB), a measure built from your recent training load (Suunto user guides, Run and Run 2). It does not publish the weights.
What is in a readiness score?
From the makers' own documentation
- HRV : named by the maker "The average of your Heart Rate Variability (HRV) during the last seven days."
- Resting heart rate : not named Not named by the maker.
- Breathing rate : not named Not named by the maker.
- Sleep : named by the maker "Your tracked sleep data of the last seven days."
- Temperature : not named Not named by the maker.
- Activity or load : named by the maker Training Stress Balance (TSB), from your recent training load.
Suunto's Recovery names 3 of the six inputs: HRV, sleep and activity or load. Suunto names three main factors and does not publish their weights.
Source: Recovery (Suunto Run user guide)
A list of scores, one per device, with six inputs for each: HRV, resting heart rate, breathing rate, sleep, temperature and activity or load. Suunto's Recovery names 3 of the six inputs: HRV, sleep and activity or load. Suunto names three main factors and does not publish their weights.
A low percentage can come from short sleep or a hard training week while HRV barely moved, so look at the HRV status before you read the percentage as a verdict on HRV. Recovery scores explained compares the inputs with other makers’ scores. Suunto also says that with a Suunto Coach plan, sessions “can be suggested automatically based on your HRV status” (Suunto, July 2026).
ZoneSense: HRV during exercise
ZoneSense works on a different signal. It needs a heart rate belt, and Suunto says it “measures heart stress through heart rate variability” with an index called DDFA from MoniCardi, a company that came out of Tampere University in Finland, to show whether an effort is aerobic, anaerobic or near VO2 max (Suunto, ZoneSense and DDFA by MoniCardi). The analysis after a workout is free in the Suunto app for anyone training with a belt. On the 9 Peak Pro, Vertical, Race and Race S, live readings come from the free ZoneSense app, which you add to the watch from the SuuntoPlus Store (Suunto, ZoneSense). The Suunto Run gained live ZoneSense in a September 2025 update (Suunto, Feature Feed).
- Two electrode pads, wetted, pick up the heart’s electrical signal through the skin
- The pod amplifies the signal and finds each R peak
- R peaks: the gap from one to the next is the RR interval
- The phone receives the RR intervals over Bluetooth, in steps of 1/1024 of a second
Three panels joined by arrows. First, the front of a torso with a strap around the chest just below the chest muscles; two rectangular electrode pads sit on the inside of the strap on either side of a small pod at its centre. Second, an ECG strip with four sharp spikes, the R peaks, with the gaps between them labelled 812 ms, 845 ms, 799 ms. Third, a phone whose screen lists the same three RR intervals in milliseconds.
A belt times each beat from the heart’s electrical signal rather than from the pulse at the wrist, which is why ZoneSense asks for one. Researchers tested the DDFA method against blood lactate in 58 people on an incremental treadmill run, recording beat intervals with a Polar H10 strap rather than a Suunto device. On average its thresholds came within 5 beats per minute of the lactate thresholds, but for the first threshold an individual estimate could fall anywhere from 27 bpm below to 23 bpm above (95% limits of agreement). Three of the authors hold shares in MoniCardi, and the paper states that the company did not influence the study’s design, data collection, analysis or interpretation (Kanniainen and colleagues, 2025).
HRV during exercise is a different quantity from resting HRV, so keep ZoneSense out of your overnight trend.
Subscription and data export
None of the Suunto pages we checked mentions a subscription for overnight HRV, the HRV status or the Recovery widget, and Suunto calls ZoneSense free.
Getting the numbers out is harder. The app exports a workout as a FIT file, with heart rate and the rest of the recording, or as GPX (Suunto Support). Suunto’s API gives approved companies workout FIT files that include R-R data, and it is not offered for personal use (Suunto API Zone). Neither page mentions nightly HRV, and the export page does not say whether an exported FIT file keeps the beat intervals. If yours does, the RR converter can read it. The overnight value stays in the app.
How accurate is Suunto HRV?
We found no peer-reviewed study that compares a Suunto watch’s overnight HRV with an ECG ECG A recording of the heart's electrical activity, taken with electrodes on the skin. ECG-based RR intervals are the reference standard for measuring HRV. More about ECG . The 2025 home study of five wearables over 536 nights did not include Suunto (Dial and colleagues, 2025), and neither did a 2022 sleep-laboratory study of six (Miller and colleagues, 2022). In the home study, the three devices worn on the wrist agreed with a chest strap less closely than the Oura rings: concordance from 0.82 to 0.94 and average error from 8.17% to 16.32%, against 0.99 and 5.96% for the Oura Gen 4.
Overnight RMSSD against a Polar H10 chest strap
Dial and colleagues, 2025
13 adults, 536 nights at home. The wrist devices were WHOOP 4.0, the Garmin Fenix 6 and the Polar Grit X Pro; newer models may differ.
Source: Dial and colleagues, Physiological Reports, 2025. Every study we have checked, with its numbers, is in the device validation tracker.
A dot chart in two panels, one row per device tested by Dial and colleagues (2025) against a Polar H10 chest strap. The first panel shows concordance (CCC), where 1 is perfect agreement; the second shows the mean absolute percentage error (MAPE), where lower is closer. Oura Ring Gen 4: concordance 0.99, average error 5.96%. Oura Ring Gen 3: concordance 0.97, average error 7.15%. WHOOP 4.0: concordance 0.94, average error 8.17%. Garmin Fenix 6: concordance 0.87, average error 10.52%. Polar Grit X Pro: concordance 0.82, average error 16.32%. 13 adults, 536 nights at home. The wrist devices were WHOOP 4.0, the Garmin Fenix 6 and the Polar Grit X Pro; newer models may differ.
Those figures describe other watches; a Suunto could sit inside that range or outside it. Two older studies tested Suunto chest belts:
- Suunto t6 with its belt: in 19 young men at rest and during exercise, beat intervals agreed excellently with a five-lead ECG, but frequency-domain HRV measures often differed by unacceptable amounts (Weippert and colleagues, 2010).
- Suunto Memory Belt: in 15 people lying and then standing, 16,742 beat intervals had limits of agreement of −2.00 to +1.94 ms against a laboratory ECG, with 18 artefacts (Bouillod and colleagues, 2015).
Both measured the heart’s electrical signal on the chest, so neither says how a Suunto watch’s optical sensor performs at night. Is wrist HRV as accurate as a chest strap explains the difference.
How to read Suunto’s numbers
- Read the status, then the milliseconds. Green means your week sits inside your own range; it says nothing about how your number compares with other people’s.
- Read weeks, not nights. Suunto’s own advice is that “a trend across several days beats any single measurement” (Suunto, September 2026).
- Do not chase a spike. Suunto says “a sudden spike shouldn’t be read as a green light on its own”; see why did my HRV spike overnight.
- Know what 60 days hides. The range is built from your own recent nights, so a long stressful stretch becomes part of normal over the weeks.
- Keep conditions the same. Same wrist, same fit, sleep and HRV tracking on every night. A new watch or a firmware update can shift the values; see can a software update change my HRV.
- Compare Suunto only with itself. Suunto does not publish its window, so the value will not match a Garmin, Polar or Oura number. HRV by device lists what each brand measures, and normal HRV explains what published values can tell you.
For other brands, see Garmin HRV Status and Polar HRV.
When to talk to a doctor
A Suunto watch does not diagnose anything, and neither the HRV status nor the Recovery percentage is a medical test. Talk to a doctor if low HRV or a run of red statuses comes with feeling unwell, lasting fatigue, palpitations, dizziness, fainting or chest pain, whatever the number says.