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Heart Rate Zone Calculator
Five personalised training zones from max heart rate. Choose Karvonen (HRR) or percentage-based method. No signup — your inputs stay in your browser.
Step By Step
How to Use This Calculator
4 steps
- Enter your age. The calculator estimates Max HR using 220 − age (Haskell & Fox, 1970).
- If you know your actual max HR from a lab test or a hard field test, enter it in the override field for greater accuracy.
- For the Karvonen method, also enter your resting heart rate — measure it on waking, before getting up, for 3 mornings and average the results.
- Toggle between percentage method and Karvonen (HRR) — the Karvonen method personalises zones for fitter individuals.
Worked Example
Example: Age 35, RHR 58 bpm, Karvonen method
Use this sample to sanity-check your inputs and understand what the final result represents.
- 1Max HR = 220 − 35 = 185 bpm
- 2HRR = 185 − 58 = 127 bpm
- 3Zone 2 (60–70%): 58 + 127×0.60 to 58 + 127×0.70 = 134–147 bpm
- 4Zone 4 threshold (80%): 58 + 127×0.80 = 160 bpm
Final Result
Zone 2 aerobic base: 134–147 bpm. Lactate threshold Zone 4: 160–176 bpm.
Methodology
Karvonen (1957) and Haskell & Fox (1970)
This section explains the calculation logic, assumptions, and source material used to make the result more trustworthy and easier to verify.
Max HR estimate: 220 − Age (Haskell & Fox, 1970). Alternative: 208 − (0.7 × Age) (Tanaka et al., 2001). Percentage method: Zone HR = Max HR × Zone%. Karvonen method: Zone HR = RHR + (Max HR − RHR) × Zone%. HRR stands for Heart Rate Reserve. The Karvonen formula personalises intensity by accounting for fitness level embedded in RHR.
Frequently Asked Questions
What is the 220 minus age formula and how accurate is it?+
The formula Max HR = 220 − Age was popularised by Haskell and Fox in 1970 and is the most widely cited method for estimating maximum heart rate. However, it has a standard deviation of about ±10–12 bpm, meaning the actual max HR for any individual can differ significantly from the estimate. More recent formulas such as Tanaka et al. (2001, Journal of the American College of Cardiology) — Max HR = 208 − (0.7 × age) — may be marginally more accurate for older adults. The custom max HR field in this calculator lets you enter a lab-tested value for much better accuracy.
What is the Karvonen formula?+
The Karvonen formula, developed by Martti Karvonen, Erkki Kentala, and Oiva Mustala (1957, Annales Medicinae Experimentalis et Biologiae Fenniae), personalises heart rate zones by incorporating your resting heart rate (RHR). It works with Heart Rate Reserve (HRR = Max HR − RHR): Zone HR = RHR + (HRR × Zone%). Because higher fitness is associated with a lower RHR, the Karvonen zones automatically shift upward for fitter individuals, making them more representative of actual effort levels.
What is the best way to measure resting heart rate?+
Measure your resting heart rate first thing in the morning, before getting out of bed, after at least 5 minutes of quiet rest. Count pulse beats at the wrist (radial artery) or neck (carotid artery) for 60 full seconds. Average three consecutive morning readings for a reliable baseline. A wrist-based fitness tracker with continuous heart rate monitoring provides a comparable estimate. Normal adult RHR is 60–100 bpm; well-trained endurance athletes often measure 40–60 bpm.
How do heart rate zones relate to training goals?+
Zone 1–2 (50–70% max HR): fat oxidation, recovery, aerobic base building. Zone 3 (70–80%): general aerobic conditioning, most easy-to-moderate training runs. Zone 4 (80–90%): lactate threshold work, tempo runs, interval training — significantly improves speed and performance. Zone 5 (90–100%): VO₂ max efforts, short all-out intervals — builds peak power but requires substantial recovery. Most evidence-based endurance programmes suggest spending the majority of volume (about 80%) in Zones 1–2 and a minority (about 20%) in Zones 4–5.
Can I use heart rate zones for strength training?+
Heart rate zones are primarily designed for continuous aerobic exercise (running, cycling, rowing). During resistance training, heart rate fluctuates rapidly and does not accurately reflect metabolic intensity or muscle load in the same way it does for steady-state cardio. RPE (Rate of Perceived Exertion) and % of 1RM are more practical intensity metrics for weight training. That said, monitoring HR during strength circuits or CrossFit-style workouts can provide a general cardiovascular load indicator.