Enter your age and your resting heart rate - the pulse you measure first thing in the morning - and the page builds the five usual training zones. It prints two published estimates of your max heart rate rather than picking one, then uses the Karvonen formula to put your own resting rate underneath every range.
Heart Rate Zones Calculator - Danfio
https://danfio.com/tools/heart-rate-zones-calculator/ - printed from this page
Zone 2 - aerobic
137–150 bpm
Using a max of 189 bpm (average of the two estimates) and your resting rate of 60 bpm.
| Zone | % of max | Range | Purpose |
|---|---|---|---|
| Zone 1 - recovery | 50–60% | 125–137 bpm | Warm-up, cool-down and easy recovery rides. |
| Zone 2 - aerobic | 60–70% | 137–150 bpm | The endurance base most plans build on. |
| Zone 3 - tempo | 70–80% | 150–163 bpm | Comfortably hard, sustainable for a while. |
| Zone 4 - threshold | 80–90% | 163–176 bpm | Lactate threshold work, hard and honest. |
| Zone 5 - VO2 max | 90–100% | 176–189 bpm | Short, very hard intervals. |
The ranges use the Karvonen formula, so a lower resting rate pushes every zone down and a higher one pushes it up - the honest version of a one-size chart.
| Formula | Estimate |
|---|---|
| 220 minus age (Fox & Haskell) | 190 bpm |
| 208 - 0.7 x age (Tanaka) | 187 bpm |
Both are population averages. The true max can be several beats off in either direction for an individual, which is why they are printed side by side rather than averaged into a promise.
The honest version of a zone chart starts from a measured number, because "percent of max" is only meaningful when the max is near yours. This page does not pretend to know your max; it says exactly how it guessed, and shows the other guess beside it.
It also prints what the arithmetic cannot know. A percentage band is not a threshold test, a watch is not a laboratory, and a resting pulse taken after a late night is a reading about the morning. The ranges are a starting point to check against how the session actually felt, and the page says so rather than handing over five numbers as if they were measurements.
Zones are ratios of a maximum heart rate that nobody measures exactly, and this page refuses to hide the guess: it prints two published estimates side by side, the older 220 minus age and the Tanaka revision, then builds five training ranges on the average of the two.
The two formulas and the Karvonen adjustment come from named sources rather than folklore: Fox and Haskell’s 1970s estimate, Tanaka and Seals’s 2001 revision in a cardiology journal, and a resting-rate formula from 1957. The arithmetic runs client-side in your browser, so the age and pulse you enter are never uploaded.
The formulas assume a healthy, untrained-to-trained adult with no relevant medication, and a beta-blocker or an out-of-the-ordinary resting pulse moves every range. A watch draws its own zones from its own measurements, so the beats will not line up exactly. Chest pain, unusual breathlessness or a morning rate far outside the ordinary is a question for a clinician, so ask one rather than recalculating.
What the page will not do is dress up its inputs. Age is clamped to the window the formulas were fitted for, the resting rate is clamped to a range a living adult can actually have, and both max-heart-rate estimates stay on screen instead of being averaged away into a single confident figure. A visitor can therefore see exactly how much of the answer came from them and how much came from a 1970s regression.
The familiar "220 minus your age" belongs to Fox & Haskell, a 1970s formula fitted on a broad group. Tanaka and colleagues revised it in 2001 to 208 minus 0.7 times your age. Both are within a few beats of each other for most people - and both can be several beats off for you as an individual.
That is why this page prints both and uses their average for the zones, while keeping the two estimates visible in a table rather than burying them in a footnote.
A zone chart that just multiplies percent by max ignores the fact that the heart does not start from zero. The Karvonen formula adds your resting rate back in: (max - resting) x intensity + resting.
This is why a fitter person - lower resting rate - gets lower zone ranges for the same max: their heart has more headroom. The page asks for a morning resting pulse because that is the one number you actually measured.
The Karvonen target is computed as the resting rate plus the chosen fraction of the gap between max and resting, so the intensity percentage is applied to the headroom your heart has, not to the max number itself. That is why, at the same percentage of max, a person with a resting rate of 50 trains at lower beats than one resting at 70 - the floor moves every range on the page.
Zone boundaries vary between coaches and wristbands, but the structure is stable: recovery, aerobic, tempo, threshold and VO2 max, from easiest to hardest. The aerobic range - roughly 60 to 70 percent of max - is where endurance base is built and is the one most people train in.
The exact beat where Zone 2 becomes Zone 3 is not a law of nature. What matters is staying broadly inside the right band for the session, which a range leaves comfortably more room for than a single number.
The formulas assume a healthy, untrained-to-trained adult with no relevant medications. Beta-blockers, for example, lower both heart rate and the meaning of a zone chart. Chest pain, unusual shortness of breath, or numbers far outside the usual range are not a calculator problem.
If your morning resting rate is consistently out of the ordinary, or exercise brings symptoms, the next step is a clinician - not a recalculation.
The page clamps age and resting heart rate into the range the formulas were built for, and asks for a morning reading taken before coffee or movement so the floor is a fair one. If that number is consistently unusual, or exercise brings symptoms, the right next step is a clinician rather than a different multiplier on the same arithmetic.
Zone 2 has become shorthand for "easy aerobic work", and the percentage band is an approximation of something the body actually does: below the first lactate threshold, most of the energy comes from fat and the effort can be held for a long time. The band is convenient because a heart rate monitor can display it; the threshold it stands for is a physiological point that differs from person to person and moves with training.
The practical test most coaches use is talking. In Zone 2 you can hold a conversation in full sentences; in Zone 3 you can speak in short phrases; above that you are down to a word or two. If the numbers and the talk test disagree, the talk test is describing you and the numbers are describing an average - which is why the page prints both estimates and never claims to have measured your threshold.
That also disposes of the "fat-burning zone" folklore. Lower intensity burns a larger share of fat and a smaller total; higher intensity burns a smaller share but more calories overall. What matters for endurance is the volume of easy work you can recover from, and the honest role of a zone chart is to keep the easy days easy enough to do that.
A watch usually estimates your max from a formula you never see, sometimes from your age, sometimes from an observed peak during a hard session, and occasionally from heart-rate variability. It also reads your pulse optically at the wrist, which lags and drifts compared with a chest strap, especially when your wrist moves or the strap is loose. Two devices showing different zone boundaries is therefore the expected outcome, not a fault.
The stable parts are the structure and the direction: harder effort means a higher zone, a lower resting rate means lower beats at the same intensity, and an older age means a lower maximum. Those relationships are what a plan actually uses. The exact beat where Zone 2 becomes Zone 3 is a line drawn by an algorithm, and every manufacturer draws it slightly differently.
A useful habit is to record a few sessions where the numbers and the effort clearly disagreed - the watch said easy and the breathing said otherwise - and use those notes rather than a new calculator. Heart rate responds to heat, dehydration, caffeine, sleep debt and illness, so a single high reading is usually a comment on the day, not on your fitness.
Most endurance plans spend the large majority of their time in Zones 1 and 2 and a small slice in Zones 4 and 5, with Zone 3 used sparingly because it is tiring without being specific. The common shorthand is roughly eighty percent easy and twenty percent hard, counted by session rather than by minute. The page cannot plan your week, but it can make the easy end of that split visible, which is the part people get wrong.
A simple use of this page is to pick the Zone 2 range, keep a session inside it, and check afterwards whether the effort felt as easy as the number suggested. If holding the bottom of the range requires real concentration, the range is probably too high for that day - heat, a poor night or a lingering cold all raise heart rate at the same workload.
None of this replaces a coach or a training plan, and none of it is medical advice. What the arithmetic offers is a defensible starting range built on a number you measured yourself, with the population guesses printed beside it so you can see how much of the answer is your data and how much is the formula.
Each example below was run through the calculator on this page when the site was built, so the numbers match what you see when you enter the same inputs.
Age: 30 years · Resting heart rate: 60 bpm
Zone 2 - aerobic
137–150 bpm
Using a max of 189 bpm (average of the two estimates) and your resting rate of 60 bpm.
Max (220 - age): 190 bpm · Max (Tanaka): 187 bpm · Your resting rate: 60 bpm · Heart-rate reserve: 129 bpm
Max works out to 189 bpm (averaging the two estimates); Zone 2 (60-70%) lands around 137-150 bpm with Karvonen.
Age: 40 years · Resting heart rate: 55 bpm
Zone 2 - aerobic
130–143 bpm
Using a max of 180 bpm (average of the two estimates) and your resting rate of 55 bpm.
Max (220 - age): 180 bpm · Max (Tanaka): 180 bpm · Your resting rate: 55 bpm · Heart-rate reserve: 125 bpm
A fitter resting rate keeps the zones lower for the same max: the aerobic band sits roughly 130-143 bpm.
Age: 30 years · Resting heart rate: 65 bpm
Zone 2 - aerobic
139–152 bpm
Using a max of 189 bpm (average of the two estimates) and your resting rate of 65 bpm.
Max (220 - age): 190 bpm · Max (Tanaka): 187 bpm · Your resting rate: 65 bpm · Heart-rate reserve: 124 bpm
Raising only the resting rate lifts every range, because the heart starts from a higher floor.
Age: 50 years · Resting heart rate: 65 bpm
Zone 2 - aerobic
129–140 bpm
Using a max of 172 bpm (average of the two estimates) and your resting rate of 65 bpm.
Max (220 - age): 170 bpm · Max (Tanaka): 173 bpm · Your resting rate: 65 bpm · Heart-rate reserve: 107 bpm
220 minus age gives 170, Tanaka gives 173 - a small spread, which is exactly why both are printed instead of one.
For most adults it is between 155 and 200 beats per minute, roughly linked to age. This page uses 220 minus age and the Tanaka revision together, because both are population estimates and the true figure can be a few beats off for any individual. However you estimate it, a proper exercise test is the only exact measurement.
It is a useful average, not a measurement. It fits the group it was derived from and drifts for individuals, which is why this page prints the Tanaka revision alongside it and works from their average.
Because the heart does not start from zero, and Karvonen adds your resting rate back into every range. A fitter person with a lower resting rate gets lower ranges for the same max - their heart has more headroom. It is the one number on this page you actually measured.
Zone 2 is the aerobic band, roughly 60 to 70 percent of max heart rate. It is the intensity where the body fuels mostly from fat and builds endurance base, which is why base-building plans spend a lot of time there and why this page leads with it.
Probably not exactly. Coaches and devices draw the five lines slightly differently, and watches take their own measurement of your max and resting rate. What holds across all of them is the structure - harder effort, higher zone - not the exact beat where one becomes the next.
For most easy sessions, yes - and the talk test is a better guide than a number when the two disagree. Heart rate lags behind effort at the start of a session and drifts upward in heat, so a runner who keeps the number fixed may slow down through no fault of their fitness. Zones are most useful for the sessions where feel is least reliable: long easy days that creep up in intensity, and intervals sharp enough that pacing by feel fades in the last repetition.
Because Karvonen treats the resting rate as the floor of every range, not as a correction applied once. Ten beats on the resting rate moves the bottom of Zone 1 and the top of Zone 5 by roughly the same amount, and leaves the percentages unchanged. Take the reading the same way each time - lying down, before coffee, after a quiet few minutes - or the shifts will describe your morning rather than your training.
No. Max heart rate is largely inherited and falls slowly with age; training moves it very little. What training changes is the work you can do at a given heart rate, and the resting rate that sets the floor here. A high max is not a badge and a low one is not a problem - which is one more reason this page prints the estimate as a range of guesses rather than a score.
Last reviewed 2026-09-25. Not a medical device and not a diagnosis; talk to a clinician. Read the full disclaimer.
Where a figure on this page comes from an official agency — HUD, IRS, FICO or a state body — the site keeps a dated snapshot of the source page in its sources library, and a scheduled job re-checks that snapshot, so the number can be traced back to the document it came from.
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