Heart rate zone calculator.
Four calculation methods × three zone systems: MaxHR, Karvonen HRR, threshold or Breno protocol, paired with Friel 7-zone, Coggan 5-zone or Breno bike/run zones.
Your training zones
Frequently asked
What is the Karvonen formula?
Karvonen uses heart-rate reserve (HRR): Target = ((MaxHR − RestHR) × %intensity) + RestHR. More accurate than %MaxHR because it accounts for individual fitness.
How do I find max HR?
Best: an all-out 5-min field test or graded ramp. Estimate: Tanaka 208 − (0.7 × age) — more accurate than 220 − age.
Which zone system should I use?
Friel's 7 zones for runners using LTHR or HRR. Coggan's 5 zones for cyclists pegged to threshold HR. The Breno protocol is sport-specific (bike vs. run) and built around max HR.
How often should I update zones?
Every 8-12 weeks, after a 5-bpm change in resting HR, or after any clean threshold test.
Why is my Zone 2 heart rate different from my friend's?
Because maximum and resting heart rate are individual and largely genetic. Two athletes of identical fitness can differ by 20 bpm at the same relative intensity, which is why absolute comparisons are useless.
Why does my heart rate drift up at the same pace?
Cardiac drift from heat, dehydration and accumulated fatigue. On long or hot sessions, expect 5-10 bpm of drift and pace by effort rather than chasing the band.
Can I use heart rate for intervals?
Poorly. Heart rate lags the effort by 30-90 seconds, so short intervals are over before it catches up. Use pace or power for intervals and heart rate for steady work.
Breno MeloHead Coach · USA Triathlon, Road Runners Club of America, TrainingPeaksEmail me my HR zones
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Karvonen heart-rate reserve, with Tanaka age-prediction as a fallback maximum
Target HR = ((HRmax − HRrest) × %intensity) + HRrest (Karvonen, 1957) Fallback HRmax = 208 − (0.7 × age) (Tanaka, 2001)
- Your resting heart rate was measured on waking, lying still, on several mornings.
- Your maximum heart rate is measured. If it is estimated from age, every zone inherits that error.
- Heart rate is not being distorted by caffeine, illness, heat, altitude or beta-blockers.
- Age-predicted HRmax has a standard deviation of roughly ±7–11 bpm, so estimated zones can be a full zone wrong.
- Heart rate lags effort by 30–120 s and is useless for intervals shorter than about two minutes.
- Cardiac drift inflates heart rate late in long or hot sessions at unchanged effort.
- Sport-specific: cycling and swimming maxima usually sit below running.
Karvonen: a small cohort of young, healthy Finnish men, 1957. Tanaka: a meta-analysis of 351 studies and 492 groups, healthy adults across the age range.
Formula, constants and cited sources last verified on . Spotted something wrong? Email breno@brenoamelo.com and it gets corrected and dated.
How the zones are calculated
The percent-of-max method scales straight off HRmax and is fine for a quick estimate.
The Karvonen method subtracts resting HR first, which accounts for a large aerobic engine and usually gives higher, more usable Zone 2 numbers for trained athletes.
Formula-derived HRmax (220 − age, or the Tanaka 208 − 0.7 × age) carries a standard deviation of 10-12 bpm. A measured max always wins.
References
Every physiological claim on this page traces to one of the primary sources below — the original paper, textbook or governing-body standard, not a secondary write-up.
- 01Karvonen MJ, Kentala E, Mustala O (1957). The effects of training on heart rate: a longitudinal study. Annales Medicinae Experimentalis et Biologiae Fenniae 35(3):307–315. PMID 13470504
- 02Tanaka H, Monahan KD, Seals DR (2001). Age-predicted maximal heart rate revisited. Journal of the American College of Cardiology 37(1):153–156. doi:10.1016/S0735-1097(00)01054-8
- 03Seiler S (2010). What is best practice for training intensity and duration distribution in endurance athletes?. International Journal of Sports Physiology and Performance 5(3):276–291. doi:10.1123/ijspp.5.3.276
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Heart Rate Zones Explained
Five zones, what each one trains, and how to set them honestly.
Zone 2: Why Slow Training Builds Fast Athletes
Easy pace is the engine room of every PR — here is how to use it.
Heart Rate vs Power vs Pace
Which metric should anchor your training, and how to combine them.
Lactate Threshold vs VO2max
The two ceilings that decide your race pace, and which one to train now.
What to actually do in zone 2
Zones are only worth calculating if the easy runs stay easy. This is why that matters more than the intervals.
Zones are the input. A plan is the output.
Knowing your Zone 2 band changes nothing until something tells you how many minutes of it you need this week. Apex builds that week from these zones and adjusts it when your readiness drops.
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Zones are the speedometer. The training plan is the engine.
Knowing your HR zones is step one. Step two is a periodized plan that hits the right zone on the right day so the engine actually grows. That's the 1:1 work.
Boston-based · Trilingual EN/PT/ES · RRCA · USAT · TrainingPeaks L2 · 12× Boston qualifier