Enter your age and resting heart rate and this calculator gives you all five training zones in actual beats per minute, using either the Karvonen heart-rate-reserve method — which personalises zones to your fitness — or the simpler percentage-of-maximum approach. You can pick between four max-HR formulas including Tanaka and the female-specific Gulati equation, or override them entirely with a measured maximum from a race or field test. It also rates your resting heart rate and shows what each zone is actually for. Pair it with the pace calculator to match effort to race pace, or the TDEE calculator for the energy cost of your training week.
Heart Rate Calculator
Your five training zones in real bpm — by heart-rate reserve or percentage of max, with the formula choice left to you.
Measure resting HR first thing in the morning, before getting out of bed. Count for a full 60 seconds, or use your watch's overnight average.
Maximum heart rate
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Why train by heart rate
Pace and perceived effort both lie to you. Heat, humidity, hills, poor sleep, stress and a heavy training week all change how hard a given pace actually is on any particular day. Heart rate reflects what your cardiovascular system is doing right now, which makes it the most reliable everyday guide to intensity — and specifically to keeping easy days genuinely easy, which is the mistake most recreational athletes make.
Estimating maximum heart rate
The familiar 220 − age (Fox) formula is convenient and widely taught, but it carries a standard deviation of around 10–12 bpm and drifts noticeably for older adults. Tanaka (208 − 0.7 × age), from a 2001 meta-analysis of 351 studies covering 18,712 people, has the lowest prediction bias and is the better default. Gulati (206 − 0.88 × age) was derived specifically from 5,437 women and suits female athletes better than the unisex formulas. HUNT (211 − 0.64 × age) came from a large Norwegian fitness study.
All of them are population averages. Your real maximum can sit 10–20 bpm either side, so if you race hard, use the highest heart rate you have actually seen — typically in the final minute of an all-out 5K — and enter it in the measured field to override the estimate.
Karvonen versus percentage of max
The simple method takes percentages straight off your maximum: zone 2 is 60–70% of max HR. The Karvonen method, published by Martti Karvonen in 1957, instead works from your heart rate reserve — the gap between resting and maximum — and adds your resting rate back on: target = resting + (max − resting) × intensity.
The difference matters because it personalises for fitness. A well-trained athlete with a resting HR of 45 and an unfit person with a resting HR of 80 have very different working ranges even at the same age, and Karvonen accounts for that while the percentage method does not. The ACSM recommends the reserve method for exercise prescription because %HRR tracks %VO₂ reserve almost one-to-one. Karvonen zones come out higher in bpm than percentage zones, so do not compare numbers between the two.
The five zones
Zone 1 (50–60%) is recovery — warm-ups, cool-downs, easy movement between hard days. Zone 2 (60–70%) is the aerobic base: conversational, fat-oxidising, and where most of your weekly volume should live. Zone 3 (70–80%) is tempo, comfortably hard, useful but easy to overuse. Zone 4 (80–90%) sits around lactate threshold and is the classic race-pace and interval zone. Zone 5 (90–100%) is maximal work for short intervals that develop VO₂ max.
About the "fat-burning zone"
Zone 2 does use fat for the highest proportion of its fuel, which is where the label comes from. But higher intensities burn more total calories per minute, so for fat loss what matters is total energy expenditure and the calorie deficit around it, not which zone you sit in. Zone 2 earns its place because it builds aerobic capacity with low recovery cost and lets you accumulate volume — not because it melts fat. Elite endurance athletes spend around 80% of training in zones 1 and 2 for exactly that reason.
One caveat worth stating plainly: beta blockers and some other medications lower heart rate substantially, which makes formula-derived zones meaningless. Pregnancy, heart conditions and recent illness also change the picture. If any of those apply, get zones set by a clinician rather than a calculator.
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Frequently asked questions
Which max heart rate formula should I use?
Tanaka (208 − 0.7 × age) is the best general default — it came from a meta-analysis of 351 studies and has lower prediction bias than 220 − age, especially over 40. Women may find Gulati (206 − 0.88 × age) closer, since it was derived from a female-only cohort of 5,437.
What is the Karvonen formula?
It sets target heart rate as resting HR + (max HR − resting HR) × intensity. Because it uses your heart rate reserve rather than just your maximum, it adjusts zones to your fitness level — a fitter person with a lower resting HR gets appropriately different targets from someone unfit of the same age.
Why are my Karvonen zones higher than my percentage zones?
They measure different things. Karvonen takes a percentage of the range between resting and max then adds resting back, so its numbers always sit above a straight percentage of max. Neither is wrong — just pick one method and stay with it rather than comparing across the two.
Is the fat-burning zone real?
Partly. Zone 2 does burn the highest proportion of fat as fuel, but higher intensities burn more total calories per minute. For fat loss the calorie deficit is what matters, not the zone. Zone 2 is valuable for building aerobic base at low recovery cost, which is a better reason to train there.
How do I find my actual maximum heart rate?
A supervised lab test is the gold standard. A practical field test: warm up thoroughly, then run three hard 3-minute hill repeats with jog recovery, going all out on the last one — your peak reading is close to true max. Alternatively take the highest value from your hardest recent race.
Why is my resting heart rate higher than usual?
Common causes are poor sleep, dehydration, alcohol, stress, illness coming on, or accumulated training fatigue. A morning resting HR 5–10 bpm above your normal is a well-established signal to take an easier day. A persistent unexplained rise is worth mentioning to a doctor.