Free Online Calculators
5 heart rate zones by Karvonen โ from age and resting pulse
This calculator works out your five heart rate training zones using the Karvonen formula, which factors in your age, resting pulse and estimated maximum heart rate. It shows exactly which pulse range to target for endurance, fat burning or performance goals. Just enter your age and resting heart rate to get your personal zones.
Your zones come from your maximum heart rate, which is estimated from your age and then split into percentage bands. Enter your age above to see each zone in beats per minute.
It depends on your maximum heart rate โ for a younger athlete with a high max, 150 bpm can still fall inside zone 2, while for an older person it usually sits in zone 3 or higher. Compare the number with your own calculated zone range rather than a fixed value.
Take your maximum heart rate, either measured in a test or estimated from your age, and multiply it by the percentage range of each zone. A more precise method uses your resting heart rate too, applying the percentages to the difference between max and resting rate.
Zone 3 is usually kept to moderate blocks within a session โ long enough to build aerobic strength, but short enough that you can still recover for your next hard workout. Most training plans use it for tempo segments rather than for the bulk of weekly volume.
Zone 3 burns a lot of calories but takes a larger share of energy from carbohydrates, so the proportion of fat used is lower than in zones 1 and 2. For fat oxidation the lower zones are more efficient, while total weight loss depends on your overall energy balance.
Yes โ zone 5 is only sustainable for short intervals of a few minutes at most, and stretching it out leads to poor form, excessive fatigue and higher injury risk. It works best in interval sessions with full recovery in between.
Yes, short intervals in zone 5 are one of the strongest stimuli for raising VO2 max because they push your cardiovascular system to its limit. A small amount per week is enough, combined with plenty of easy low-zone training.
Neither is universally better โ zone 3 suits longer tempo work that builds aerobic endurance, while zone 4 targets your lactate threshold in shorter, harder intervals. Choose based on your goal and how much recovery time you have.
A resting pulse that is persistently very high or unusually low, especially with dizziness, breathlessness or chest discomfort, should be checked by a doctor. A single reading outside the normal range is not a diagnosis โ the trend and your symptoms matter more.
A heart rate zone calculator translates your age and resting pulse into five personalised training zones, each tied to a specific physiological purpose. Instead of guessing whether you're going "easy" or "hard," you get exact beats-per-minute ranges that tell you precisely how your cardiovascular system is working during a run, ride, or swim. This matters because most training benefits โ fat burning, aerobic base building, lactate tolerance, top-end speed โ happen in fairly narrow, individual heart rate bands. Training blindly, without knowing these numbers, is one of the main reasons recreational athletes plateau or get injured despite putting in plenty of hours.
The calculator uses the Karvonen method, which is more precise than simply taking a percentage of your maximum heart rate because it accounts for your individual resting pulse โ a proxy for fitness and recovery status. The formula is:
Target HR = ((HRmax โ HRrest) ร intensity) + HRrest
Here, HRmax is your maximum heart rate, HRrest is your resting heart rate (measured first thing in the morning, before getting out of bed, gives the most reliable number), and intensity is the desired percentage of your heart rate reserve, expressed as a decimal (for example 0.65 for 65%).
The term (HRmax โ HRrest) is called your Heart Rate Reserve (HRR) โ it represents the total "working range" your heart has available between rest and full exertion. Zones are then calculated as percentages of that reserve, not simply as percentages of HRmax, which is why Karvonen zones are shifted upward compared to the naive "percentage of max" method and better reflect real physiological effort.
If you don't have a lab-measured or field-tested maximum heart rate, the calculator estimates it. The classic formula everyone has heard of is:
HRmax = 220 โ age
This rule of thumb was published decades ago and has a standard deviation of more than 10 beats per minute โ meaning for a large share of people it is simply wrong, sometimes by 15โ20 bpm in either direction. It also has a systematic bias: it underestimates HRmax in people over 40 and overestimates it in younger people.
The more modern and statistically robust option, published by Tanaka et al. (2001) from a meta-analysis of thousands of subjects, is:
HRmax = 208 โ 0.7 ร age
This calculator shows both results side by side so you can see the gap for yourself. For a 50-year-old, 220 โ age gives 170 bpm, while Tanaka gives 173 bpm โ a meaningful difference when it feeds into every zone boundary above it. The older you are, the bigger this gap becomes, which is exactly why Tanaka is now the preferred default in exercise science. That said, no formula beats a real, measured maximum obtained through a supervised maximal test.
Example 1 โ A 30-year-old runner, HRrest 60 bpm. Tanaka HRmax = 208 โ (0.7 ร 30) = 187. HRR = 187 โ 60 = 127. Zone 2 (60โ70% of HRR) = ((127 ร 0.60) + 60) to ((127 ร 0.70) + 60) = 136 to 149 bpm. This is the range where most "easy" long runs should sit.
Example 2 โ A 55-year-old cyclist, HRrest 65 bpm. Old formula: HRmax = 220 โ 55 = 165. Tanaka: HRmax = 208 โ (0.7 ร 55) = 169.5. The four-and-a-half beat gap shifts every single zone upward, meaning a rider using the old formula would systematically believe they are training harder than they actually are, and would likely undertrain their top-end zones.
Example 3 โ A beginner with HRrest 75 bpm and HRmax 190 (measured). HRR = 115. Zone 1 (50โ60%) = 132.5 to 134 to roughly 144 bpm; Zone 5 (90โ100%) = 178.5 to 190 bpm. Because their resting pulse is relatively high, their reserve is smaller, and their zones are compressed and shifted upward compared to a fitter athlete with the same HRmax but a lower resting pulse.
| Zone | Share of Heart Rate Reserve | Training Purpose | Perceived Exertion |
|---|---|---|---|
| Z1 Recovery | 50-60% | active recovery, easy spinning | very light |
| Z2 Base endurance | 60-70% | fat metabolism, aerobic base | light, can hold a conversation |
| Z3 Aerobic endurance | 70-80% | raising aerobic capacity | moderate, speech becomes short |
| Z4 Anaerobic threshold | 80-90% | race pace, lactate tolerance | hard |
| Z5 Maximum | 90-100% | short intervals, peak power | maximal, only minutes |
The single most common mistake seen in amateur training logs is running, riding, or swimming "easy" sessions well above the actual Zone 2 ceiling. Because Zone 2 pace often feels almost embarrassingly slow, especially for competitive personalities, athletes creep up into Zone 3 without noticing. The problem is that Zone 3 is neither properly easy nor properly hard โ it builds fatigue without maximizing the aerobic and fat-metabolism adaptations that true Zone 2 work delivers. Over months, this is a major reason base-building blocks fail to produce the expected gains: the intended "easy" volume was never actually easy. Using a calculated, individual Zone 2 ceiling โ rather than a felt sense of effort โ is one of the most effective fixes available to endurance athletes at any level.
The 220 โ age rule is an old, simple estimate with a standard deviation over 10 bpm, meaning it can be quite inaccurate for many individuals. It tends to underestimate HRmax in people over 40 and overestimate it in younger people. The Tanaka formula (208 โ 0.7 ร age), based on a large modern meta-analysis, is generally more accurate across a wide age range, though a directly measured maximum heart rate from a real test is always the most reliable option.
The Karvonen method uses your Heart Rate Reserve โ the gap between resting and maximum heart rate โ rather than just a percentage of your maximum. This makes the zones personal to your current fitness and recovery state, since two people with the same age and HRmax can have very different resting pulses and therefore genuinely different training zones.
No. This tool provides general fitness estimates based on established formulas and is not medical advice. Heart rate responses vary due to medication, health conditions, and individual physiology. Anyone starting a new or more intense training program, especially those with existing health concerns or over 40, should get a medical check-up before beginning.