Heart Rate Zone Calculator
Calculate your personalized training heart rate zones
What is a Heart Rate Zone Calculator?
Heart rate training zones divide your cardiovascular effort into structured bands — each zone targets a different energy system and produces different physiological adaptations. Training only at one intensity (always hard, or always easy) limits development. Zone-based training ensures you get the right stimulus on the right day, which is how elite athletes structure their training year.
This calculator uses two methods: the Percentage of Maximum Heart Rate method (simple, widely used) and the Karvonen Heart Rate Reserve method (more accurate, accounts for your resting heart rate). The Karvonen method was developed by Finnish physiologist Martti Karvonen in 1957 and is recommended by exercise physiologists when resting heart rate is known.
The most commonly used system in running and cycling divides training into 5 zones. Zone 1–2 (easy/aerobic) builds aerobic base and fat-burning capacity. Zone 3 (tempo) improves lactate threshold. Zone 4 (threshold) raises the speed at which lactate accumulates. Zone 5 (VO2max) develops maximum aerobic capacity and speed.
How to Use This Calculator
What Each Zone Trains
- • Zone 1–2 (easy): Aerobic base, fat metabolism, recovery — most training volume
- • Zone 3 (tempo): Aerobic efficiency, marathon/half-marathon race pace
- • Zone 4 (threshold): Lactate threshold — 10K race effort
- • Zone 5 (VO2max): Maximum oxygen uptake — 5K effort and shorter intervals
- • 80/20 principle: 80% of training in Zone 1–2, 20% in Zone 3–5
?Frequently Asked Questions
Is "220 minus age" accurate for max heart rate?
The Fox formula (220 − age) is a rough population average with a standard deviation of ±10–12 bpm. That means for a 40-year-old, predicted max HR is 180 but actual max could range from 158–202 bpm and still be normal. The formula consistently underestimates max HR in fit, older athletes. For accurate zones, a genuine max HR test (e.g. 3K time trial or Cooper test) is preferable. The formula is a reasonable starting point when no measured value is available.
What is the 80/20 rule in running training?
Research by sports scientist Stephen Seiler (published in multiple studies 2004–2013) found that elite endurance athletes — runners, cyclists, rowers — perform approximately 80% of their training at low intensity (Zones 1–2) and only 20% at moderate-to-high intensity (Zones 3–5). This "polarised training" model is supported by decades of data from elite athletes and is increasingly adopted in recreational running through programmes by Matt Fitzgerald and others.
Why is resting heart rate a fitness indicator?
A lower resting heart rate indicates that the heart is pumping more blood per beat (higher stroke volume), requiring fewer beats per minute to maintain circulation. Typical sedentary adults have resting HR of 70–80 bpm. Fit recreational runners average 50–65 bpm. Elite endurance athletes often have resting HR of 35–50 bpm. The famous extreme case is Miguel Indurain (5x Tour de France winner) who had a resting HR of ~28 bpm.
How often should I train in Zone 5?
Zone 5 (VO2max intervals) is the most stressful training stimulus and requires the most recovery. Most coaches recommend Zone 5 work no more than 1–2 sessions per week, with 48–72 hours of recovery between sessions. For beginners, Zone 5 training is not recommended until a solid aerobic base (6+ months of consistent running) is established. Overuse of Zone 4–5 training without adequate easy running is one of the most common causes of overtraining syndrome.