How Suunto Calculates Your Max Heart Rate (HRmax)
Suunto defaults to 220 − age and then draws unusually narrow zones on top of it, which is why the same run lands in a different zone than on a Polar.
Suunto does not measure your maximum heart rate. It uses 220 − age by default and tells you plainly to change it if you know your real number. The more interesting difference is what it builds on top: Suunto's intensity zones are far narrower than any other brand's, so the same run can report a different zone on a Suunto than on a Polar.
The zones are the story
Suunto's default zones, as percentages of HRmax:
- Zone 1: below 71%
- Zone 2: 72 to 76%
- Zone 3: 77 to 81%
- Zone 4: 82 to 86%
- Zone 5: 87 to 100%
Zones 2, 3 and 4 are five points wide. Polar's equivalents are ten points wide, running 60 to 70, 70 to 80 and 80 to 90%.
Take an HRmax of 190. Suunto's zone 3 is 146 to 154 bpm, a band of nine beats. Polar's zone 3 is 133 to 152, a band of nineteen. A steady run at 150 bpm sits at the top of Suunto zone 3 and near the top of Polar zone 3, but a run at 140 is Suunto zone 1 and Polar zone 3. The same effort, two very different labels.
Maximale hartslag
185bpm
| Zone | Bereik | Wat het traint |
|---|---|---|
| Z1 | Herstel 93–111 bpm | Actief herstel en opwarming; bevordert de doorbloeding zonder vermoeidheid toe te voegen. Heel makkelijk, RPE 1–2. Volledig gesprek mogelijk, nauwelijks buiten adem. |
| Z2 | Duurvermogen 111–130 bpm | Aerobe basis, vetverbranding en capillaire dichtheid, de brood-en-boterzone. Comfortabel, RPE 3–4. Volledige zinnen mogelijk. |
| Z3 | Tempo 130–148 bpm | Aerobe capaciteit en spierduurvermogen; 'matig zwaar' constant werk. Inspannend, RPE 5–6. Alleen korte zinnen. |
| Z4 | Drempel 148–167 bpm | Lactaatdrempel, je houdbare wedstrijdtempo-plafond. Zwaar, RPE 7–8. Een paar woorden per keer. |
| Z5 | VO₂max 167–185 bpm | Maximaal aeroob vermogen en VO₂max via korte, harde intervallen. Heel zwaar tot maximaal, RPE 9–10. Praten lukt niet. |
Z1 · Herstel. Actief herstel en opwarming; bevordert de doorbloeding zonder vermoeidheid toe te voegen. Heel makkelijk, RPE 1–2. Volledig gesprek mogelijk, nauwelijks buiten adem.
Z2 · Duurvermogen. Aerobe basis, vetverbranding en capillaire dichtheid, de brood-en-boterzone. Comfortabel, RPE 3–4. Volledige zinnen mogelijk.
Z3 · Tempo. Aerobe capaciteit en spierduurvermogen; 'matig zwaar' constant werk. Inspannend, RPE 5–6. Alleen korte zinnen.
Z4 · Drempel. Lactaatdrempel, je houdbare wedstrijdtempo-plafond. Zwaar, RPE 7–8. Een paar woorden per keer.
Z5 · VO₂max. Maximaal aeroob vermogen en VO₂max via korte, harde intervallen. Heel zwaar tot maximaal, RPE 9–10. Praten lukt niet.
- Zones zijn eenvoudige percentages van de maximale hartslag (Z1 50–60% tot Z5 90–100%). Ze zijn makkelijk in te stellen, maar gaan ervan uit dat je HRmax klopt.
- Hartslag loopt 1–3 minuten achter op de inspanning en stijgt bij hitte of uitdroging ('cardiac drift'), dus beoordeel korte, harde inspanningen op gevoel.
Een PDF met je resultaten, plus een QR-code om ze altijd opnieuw te openen.
Neither is wrong. Narrow bands give you finer resolution and punish sloppy pacing. Wide bands are more forgiving and easier to hit. What matters is knowing which system you are reading, because "I did a zone 2 run" means nothing across brands.
Why the default estimate still hurts
Narrow zones make an inaccurate HRmax worse, not better. If your estimate is eight beats high, every boundary moves up by six or seven beats, and a band only nine beats wide can move almost entirely past where you are actually training.
Suunto's own material is candid about this. It notes that age formulas scatter too much to pin down an individual and that the only way to know your maximum is to test it.
How to set it manually
Suunto keeps HRmax in your personal settings, in the Suunto app and on the watch, and uses it for every sport unless you override the zones per activity.
Test first. Build to hard over 10 to 15 minutes, finish with an all-out 60 to 90 second effort, uphill if you can, take the highest reading off a chest strap, repeat within two weeks and keep the higher number. Not for anyone with cardiac risk or new to hard training. The full protocol is in finding your maximum heart rate.
Then enter it, and check your zone boundaries afterwards rather than assuming they updated the way you expected.
The better anchor
Percentage-of-maximum has a structural problem that no formula fixes: it says nothing about your fitness. Two runners with the same maximum and wildly different training get identical zones.
Threshold heart rate does not have that problem, because it moves as you get fitter. If you have tested yours, LTHR zones will place your boundaries better than any percentage of a maximum, and LTHR vs %HRmax zones covers the difference. If you know your resting heart rate but not your threshold, Karvonen is the middle option.
FAQ
What formula does Suunto use for max heart rate? 220 − age by default. Suunto recommends replacing it with a tested value.
What are Suunto's heart rate zones? Five zones as percentages of HRmax: below 71%, 72 to 76%, 77 to 81%, 82 to 86% and 87 to 100%.
Why are my Suunto zones different from my Garmin or Polar zones? Because the bands are narrower. Suunto's middle zones are five percentage points wide where most brands use ten, so the same heart rate maps to a different zone number.
Can I change my max heart rate on a Suunto? Yes, in your personal settings in the Suunto app or on the watch, and you can override zone boundaries per activity.
Does Suunto detect my max heart rate automatically? No. It uses what you give it, so an untouched profile is running on an age formula indefinitely.
Other brands
- Garmin uses Tanaka and raises HRmax from recorded peaks.
- COROS recommends Gellish and offers three zone models.
- Polar uses 220 − age with clean 10-point bands.
- Apple Watch publishes no formula at all.
Sources
- Suunto on intensity zones
- Suunto on resting and max heart rate
- Suunto on calculating max heart rate
- Suunto Run intensity zones
Cover photo by D100a, CC BY-SA 3.0, via Wikimedia Commons.
