Heart Rate Zone Calculator
Find your maximum heart rate and training zones using the Karvonen method.
Measure first thing in the morning for best accuracy
Results update as you type.
This calculator provides estimates based on population research. Results are not medical advice. Consult a qualified healthcare provider before making health or nutrition decisions.
How it works
Heart rate zones are bands of cardiovascular intensity used to structure aerobic training. Training in different zones produces different physiological adaptations, making heart rate monitoring a powerful tool for matching training effort to specific fitness goals. Zone 1 (50–60% HRR) is warm-up and active recovery — very light effort used to increase blood flow without taxing recovery. Zone 2 (60–70%) is the aerobic base zone: sustainable for hours, it builds mitochondrial density, fat oxidation efficiency, and cardiovascular health — the foundation of endurance. Zone 3 (70–80%) is a moderate aerobic effort that crosses into anaerobic contribution; useful but often overused at the expense of Zone 2 and Zone 5. Zone 4 (80–90%) is near the lactate threshold — the intensity at which lactate accumulates faster than it clears; tempo runs and sustained intervals target this zone to raise the threshold and improve race pace. Zone 5 (90–100%) is maximal effort for short intervals; it develops VO2 max (maximum oxygen consumption capacity), the single greatest predictor of cardiovascular fitness and longevity. Research increasingly shows that 80% of training in Zones 1–2 and 20% in Zones 4–5 (the 80/20 or polarized model) produces superior results to spending most time in Zone 3.
Max HR = 220 − age; Zone boundaries via Karvonen: Zone bpm = resting HR + (max HR − resting HR) × %
The 220-minus-age formula is a population average with a standard deviation of ±10–12 bpm — individual max HR can differ significantly. The Karvonen method uses Heart Rate Reserve (HRR = maxHR − resting HR) to compute zone boundaries: Zone 1 is 50–60% HRR, Zone 2 is 60–70%, Zone 3 is 70–80%, Zone 4 is 80–90%, Zone 5 is 90–100%. This method is more accurate than simply using percentages of max HR.
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter age.
- 2
Adjust the options
Adjust resting heart rate (optional) if they apply — sensible defaults are already set.
- 3
Read your result
Estimated max heart rate updates instantly as you type — no button to press.
Frequently asked questions
Is 220 minus age an accurate way to find max heart rate?
It is a useful population average but has significant individual variation — the standard deviation is about ±10–12 bpm, meaning roughly two-thirds of people fall within 10 bpm of the formula's prediction, but the remaining third fall outside that range. For general fitness purposes, the formula is adequate. For serious athletes, determining actual max HR through a maximal effort test (e.g., a 3–5 km all-out run with a final hill sprint) is more accurate. Some coaches prefer the formula 207 − (0.7 × age), which has slightly better fit at older ages.
What is Zone 2 training and why is it popular?
Zone 2 (60–70% HRR, conversational pace) has gained enormous popularity based on research and practitioner advice from figures like Dr. Peter Attia and Iñigo San Millán. At this intensity, mitochondria are maximally stimulated to develop their fat-oxidation capacity — the ability to burn fat efficiently for sustained energy. Most endurance athletes should spend 75–80% of training in Zone 2. Despite its low intensity, high volume Zone 2 training dramatically improves aerobic capacity, metabolic health, insulin sensitivity, and longevity markers. If you can hold a full conversation without shortness of breath, you are likely in Zone 2.
What is my resting heart rate and is it important?
Resting heart rate (RHR) is your heart rate when completely at rest — typically measured first thing in the morning before getting out of bed. Average RHR for adults is 60–100 bpm. Athletes often have RHRs of 40–60 bpm due to increased cardiac stroke volume (each beat pumps more blood). A lower RHR is generally associated with better cardiovascular fitness and lower cardiac mortality risk. A sudden increase in RHR (5–10 bpm above baseline) often signals incomplete recovery, illness, or overtraining — tracking RHR daily is a valuable monitoring tool.
Can I use my phone or watch for heart rate training?
Modern optical heart rate sensors in smartwatches (Apple Watch, Garmin, Polar) are accurate enough for Zone 2 and general aerobic training, typically within ±5% under steady-state conditions. Accuracy drops during high-intensity intervals due to motion artifact and the nature of pulse wave measurement. For serious threshold and interval work, a chest strap heart rate monitor (Polar H10, Garmin HRM-Pro) is significantly more accurate and responds more quickly to effort changes. Regardless of device accuracy, consistency in measurement is more important than absolute accuracy — track trends over time.
Is high-intensity interval training better than steady-state cardio?
Both have distinct benefits and the evidence supports using both, not choosing between them. High-intensity interval training (HIIT, Zone 4–5) produces large VO2 max improvements in less time but is taxing on recovery and can't be done daily. Steady-state Zone 2 builds aerobic base, fat-burning capacity, and mitochondrial density with minimal recovery cost — allowing high training frequency. The most robust model from elite endurance athlete research is the polarized or 80/20 model: 75–80% of sessions in Zone 1–2 (very easy), 5–10% in Zone 3, and 15–20% in Zone 4–5 (high intensity). This produces superior adaptations to training predominantly in the 'moderate' Zone 3 that many recreational athletes default to.