Why use this calculator
Most people train in one grey zone: too hard to build an aerobic base, too easy to drive real adaptation. Zones fix that by giving a number to aim at, and they are the reason structured endurance programmes work. The important detail is which method produces those numbers.
A plain percentage of maximum ignores your resting heart rate entirely, so it hands a fit person with a resting rate of 45 the same zone 2 as someone whose resting rate is 75, which cannot be right. The Karvonen method distributes zones across your heart rate reserve, the working range between rest and maximum, so it adapts as your fitness improves.
This calculator shows both, lets you swap in a measured maximum, and is explicit about the error in every age based formula rather than quietly presenting 220 minus age as fact.
How to use it
- Enter your age in whole years.
- Measure your resting heart rate properly: take your pulse for a full 60 seconds before getting out of bed, do it on several mornings and enter the average, because a single reading taken after standing up can be 15 beats too high. Choose where your maximum heart rate comes from.
- Fox, the familiar 220 minus age, overestimates for young adults and underestimates for older ones; Tanaka and Nes were derived from larger and more representative samples and generally fit better past 40.
- If you have ever seen a genuine maximum in a hard hill repeat, a race finish or a laboratory test, choose measured and enter it, since a real number beats every estimate.
- Finally pick Karvonen or percentage of maximum for the zone calculation.
What each result means
- Maximum Heart Rate
- The highest rate your heart is estimated to reach in all-out effort, and the ceiling every zone is calculated from.
- Heart Rate Reserve
- Maximum minus resting: the range your heart actually works across, and the basis of the Karvonen calculation.
- Resting Heart Rate Used
- The resting rate applied after clamping it below your maximum. A falling resting rate over months is a good sign of improving fitness.
- Zone 1 Recovery (50-60%)
- Very easy effort for warm-ups, cool-downs and recovery days. You should be able to hold a full conversation comfortably.
- Zone 2 Aerobic Base (60-70%)
- Conversational endurance pace where most base training should happen. It builds mitochondrial density and fat oxidation.
- Zone 3 Tempo (70-80%)
- Comfortably hard steady effort where speech drops to short sentences. Useful, but easy to overuse at the cost of both easier and harder work.
- Zone 4 Threshold (80-90%)
- Around lactate threshold and typical race pace, sustainable for 20 to 60 minutes. This is where threshold intervals belong.
- Zone 5 VO2 Max (90-100%)
- Maximal effort in intervals of 30 seconds to about five minutes. Effective, demanding, and the fastest route to overreaching if overdone.
- Formula Uncertainty
- The spread around any age-predicted maximum. It is why a measured maximum from a field or lab test is worth far more than a formula.
The formula
Maximum heart rate is estimated by one of three published equations:
- Fox, 220 minus age
- Tanaka, 208 minus 0.7 multiplied by age
- Or Nes, 211 minus 0.64 multiplied by age, all in beats per minute
Heart rate reserve is maximum heart rate minus resting heart rate.
The Karvonen method gives a target of heart rate reserve multiplied by the intensity fraction, plus resting heart rate, so 70 per cent for a reserve of 130 and a resting rate of 60
0.70 x 130 + 60 = 151 bpm
The percentage of maximum method is simply maximum heart rate multiplied by the intensity fraction. The five zones use 50 to 60, 60 to 70, 70 to 80, 80 to 90 and 90 to 100 per cent. Age-predicted maxima carry a standard deviation of roughly 10 to 12 bpm, so two thirds of people fall within that band and one third fall outside it.
How this number is used in practice
The practical value of zones is that they stop you drifting. Left to feel, most recreational runners and cyclists turn easy days into moderate ones and hard days into moderate ones too, which is how people train five days a week for a year and get no faster.
Endurance coaching converged on a polarised pattern for this reason: roughly 80 per cent of sessions genuinely easy in zones 1 and 2, and the remaining 20 per cent genuinely hard in zones 4 and 5, with relatively little time deliberately spent in the middle.
Zone 2 work feels too slow at first, especially for anyone used to training by pace, and that discomfort is the point.
Zones also move, and not only with fitness. Heart rate runs five to ten beats higher in heat and humidity, drifts upward during long sessions even at constant effort, sits higher after caffeine, poor sleep, illness or alcohol, and responds slowly during short intervals so it is a poor guide for anything under about two minutes.
Beta blockers and some other cardiac medications lower both resting and maximum heart rate substantially, which makes every formula on this page invalid; anyone taking them should get zones set by a clinician or cardiac rehabilitation team. Chest strap monitors track intervals far more reliably than wrist optical sensors, which lag and sometimes lock onto cadence instead of pulse.
If you get chest pain, unusual breathlessness, dizziness or palpitations during exercise, stop and see a doctor rather than adjusting a zone.
Worked examples
30 year old, resting rate 60 bpm, Fox maximum, Karvonen zones
Maximum 190 bpm and a reserve of 130, giving zone 2 of 138 to 151 bpm and zone 4 of 164 to 177 bpm.
45 year old, resting rate 70 bpm, Fox maximum, percentage of maximum zones
Maximum 175 bpm, with zone 2 at 105 to 122 bpm and zone 3 at 122 to 140 bpm, noticeably lower than the Karvonen equivalents.
50 year old, resting rate 55 bpm, Tanaka maximum, Karvonen zones
Maximum 173 bpm rather than the 170 that 220 minus age would give, with zone 2 landing at 126 to 138 bpm.
When people use it
- Setting an easy pace for base training so recovery days are genuinely easy
- Programming threshold and interval sessions with a target range rather than a guess
- Checking whether a watch or app has set your zones from a sensible maximum
- Comparing Karvonen zones against percentage of maximum before choosing one
- Tracking resting heart rate over months as a simple marker of aerobic fitness and fatigue
Tips
- Measure your resting heart rate before getting out of bed, across several mornings, and use the average. A reading taken after standing up can be 15 bpm too high.
- Treat any age-predicted maximum as a first guess. The standard deviation is 10 to 12 bpm, so roughly one person in three sits outside that band.
- Get a real maximum from a supervised field test or laboratory test if you train seriously, and only after you are confident it is safe for you to go all out.
- Spend most of your weekly volume in zones 1 and 2. Easy work is where aerobic adaptation accumulates, and most people do far too little of it.
- Ignore heart rate for intervals shorter than about two minutes. It lags the effort, so use pace, power or perceived exertion instead.
- Expect zones to read high in heat, at altitude, when dehydrated, after poor sleep, and when you are coming down with something.
- If you take beta blockers or any medication that changes heart rate, get your zones set by a clinician, because every formula here will be wrong for you.
What it assumes, and where it stops being accurate
- Age-predicted maximum heart rate carries a standard deviation of about 10 to 12 bpm, so the zones built on it can be out by that much in either direction.
- The five-zone model with 10 per cent bands is a convention, not a physiological boundary. Other systems use three, six or seven zones with different cut points.
- Karvonen assumes your resting heart rate was measured properly at true rest. An inflated resting figure pushes every zone upward.
- The formulas are not valid for anyone taking beta blockers or other rate-controlling medication, or with a pacemaker or arrhythmia.
- Heart rate lags effort by 30 seconds or more, so zones are unreliable for short intervals and during rapid changes of pace.
- It does not account for heat, humidity, altitude, dehydration, caffeine, illness or cardiac drift, all of which raise heart rate at the same effort.
Terms used on this page
- Maximum heart rate
- The highest rate your heart can reach during all-out effort, largely set by age and genetics rather than by fitness.
- Heart rate reserve
- Maximum heart rate minus resting heart rate: the working range used by the Karvonen formula.
- Karvonen formula
- Target rate equals heart rate reserve multiplied by the intensity fraction, plus resting heart rate.
- Lactate threshold
- The intensity above which blood lactate accumulates faster than it can be cleared, roughly the top of zone 4.
- Cardiac drift
- The slow rise in heart rate during prolonged exercise at constant effort, driven mainly by heat and fluid loss.
Questions people ask
- Is 220 minus age accurate?
- It is convenient rather than accurate. The standard deviation around it is roughly 10 to 12 beats per minute, so about one person in three falls outside that band, and it tends to overestimate in young adults and underestimate in older ones. Tanaka and Nes fit large populations better, but a measured maximum beats every formula.
- Which method should I use, Karvonen or percentage of maximum?
- Karvonen, if you have a reliable resting heart rate. It uses your heart rate reserve, so it accounts for the fact that a fitter person with a lower resting rate has a wider working range. Percentage of maximum is simpler and fine for rough guidance, but it produces easy zones that often feel unreasonably slow.
- How do I find my true maximum heart rate?
- A graded exercise test in a laboratory is the gold standard. A supervised field test such as repeated hard hill efforts or a maximal 5 minute effort at the end of a long warm-up gets close. Only attempt either if you are healthy, well trained and cleared for maximal exercise, and ideally not alone.
- What is zone 2 training and why is it popular?
- Zone 2 is conversational aerobic effort, roughly 60 to 70 per cent of heart rate reserve. It develops mitochondrial density, capillary networks and fat oxidation with relatively little fatigue cost, so large volumes are sustainable week after week. Most recreational athletes train above it and accumulate fatigue without the adaptation.
- Why is my heart rate higher than usual at the same pace?
- Heat, humidity, altitude, dehydration, caffeine, poor sleep, alcohol the night before, illness and accumulated training fatigue all raise heart rate at a given effort. Cardiac drift also lifts it steadily through a long session. A rate sitting well above normal at an easy pace is a reasonable signal to make the day easier.
- Do these zones work if I take heart medication?
- No. Beta blockers and similar drugs lower both resting and maximum heart rate, sometimes by 20 beats or more, which makes every age-predicted formula and every zone derived from it wrong. Ask your cardiologist or a cardiac rehabilitation team to set training intensities for you, usually using perceived exertion or a supervised test.
Use this with
Heart Rate Zones Calculator answers one part of the question. These pick up where it stops: Calories Burned Calculator, Running Pace Calculator, TDEE Calculator and BMI Calculator.
Where these figures come from
This calculation is jurisdiction-neutral arithmetic. No country-specific rules are applied.
- American Heart Association: target heart rates. Target heart rate ranges and maximum heart rate estimation
- World Health Organization: physical activity. Weekly moderate and vigorous activity recommendations
- Australian Government Department of Health: physical activity and exercise. Australian physical activity guidelines by age group
Heart Rate Zones Calculator produces an estimate for general information. It is not financial, tax, medical, legal or engineering advice. read the full disclaimer. Spotted a wrong number? Report it and it gets fixed. The form picks up this calculator and the inputs you used.