What is your target heart rate?
Your target heart rate is the range, in beats per minute, that corresponds to a chosen exercise intensity. Training within a specific range lets you match your effort to your goal - easier zones build endurance and burn fat, harder zones build speed and fitness - instead of guessing whether you're working hard enough.
The Karvonen formula
The Karvonen method calculates target heart rate from your heart-rate reserve (HRR), which is the difference between your maximum and resting heart rates. Because it accounts for your resting heart rate, it personalises the result to your fitness level rather than using a one-size-fits-all percentage of max.
- Maximum heart rate is estimated from age, using Tanaka or Gulati depending on sex.
- Heart-rate reserve (HRR) = maximum HR - resting HR.
- Target HR = resting HR + (intensity percentage x HRR).
Worked example
Take a 30-year-old woman with a resting heart rate of 60 bpm. Her estimated max is about 180 bpm with the Gulati equation, so her heart-rate reserve is 180 - 60 = 120 bpm. For 60% intensity, her target is 60 + (0.60 x 120) = 132 bpm. For 80%, it is 60 + (0.80 x 120) = 156 bpm.
Why use resting heart rate?
Simple methods like '70% of maximum heart rate' ignore the fact that two people of the same age can have very different fitness. A well-trained athlete might have a resting heart rate of 45 bpm while someone less fit sits at 75. The Karvonen formula uses your resting heart rate to anchor the zones to your own cardiovascular system, producing target ranges that better reflect how hard you're actually working.
Karvonen vs percent of max heart rate
Percent-of-max methods are simple: estimate maximum heart rate, then multiply by a percentage. That is the approach behind many public target-heart-rate charts. Karvonen adds one more input, your resting heart rate, so it can reflect fitness changes over time.
For general health guidance, either method can be useful. For structured training, Karvonen is usually more helpful because your zones move as your resting heart rate improves. If your resting heart rate drops from consistent aerobic training, the same age and maximum heart-rate estimate can produce slightly different training zones.
Example zones at the same age
The table below shows why resting heart rate matters. Both examples use an estimated max heart rate of 180 bpm for a 40-year-old. The only difference is resting heart rate.
| Resting HR | 50% HRR | 70% HRR | 85% HRR |
|---|---|---|---|
| 55 bpm | 118 bpm | 143 bpm | 161 bpm |
| 70 bpm | 125 bpm | 147 bpm | 164 bpm |
Target heart rate by intensity
Health authorities generally split exercise into moderate and vigorous intensity. The table below shows how those map to your heart-rate reserve, alongside the five more granular training zones the calculator produces.
| Intensity | % of heart-rate reserve | Use it for |
|---|---|---|
| Moderate | 50-70% | Everyday cardio, fat burning, base fitness |
| Vigorous | 70-85% | Improving fitness, performance, calorie burn |
| Maximum | 85-100% | Short, hard intervals and peak efforts |
How to use the five zones
Use Zone 1 for warm-ups, cool-downs and easy recovery. Use Zone 2 for aerobic base work you can repeat often. Use Zone 3 for controlled tempo efforts. Use Zone 4 for threshold intervals that feel hard but repeatable. Use Zone 5 only for short peaks, sprints and very hard intervals.
If you are new to training, most sessions should sit in the lower zones while your joints, tendons and aerobic system adapt. If you already train regularly, combine easy volume with a smaller amount of harder work rather than trying to make every workout feel maximal.
How to measure your resting heart rate
For an accurate target, measure your resting heart rate properly. The best time is first thing in the morning, before you get out of bed. Count your pulse for 60 seconds (or count for 15 seconds and multiply by four), and ideally average it over a few mornings. A fitness tracker or smartwatch that records overnight resting heart rate is even more convenient and reliable.