Target Heart Rate Calculator
Calculate target heart rate zones for fat burn, cardio, and peak training from age and resting HR.
Returns 5 BPM zones using the Karvonen formula.
Target heart rate zones help you exercise at the right intensity for your fitness goals. This calculator supports two methods: the standard percentage-of-max method and the more accurate Karvonen method.
Standard Method:
Maximum Heart Rate (MHR) = 208 − (0.7 × Age)
Target HR = MHR × Intensity %
Karvonen Method (more accurate when resting heart rate is provided):
Heart Rate Reserve (HRR) = MHR − Resting HR
Target HR = (HRR × Intensity %) + Resting HR
What each variable means:
- Age: your current age in years. Maximum heart rate falls about 0.7 bpm per year.
- Resting Heart Rate: your pulse taken first thing in the morning, before getting out of bed. Typical is 60 to 80 bpm; trained endurance athletes often sit at 40 to 60. Supplying it switches the calculator to the Karvonen method.
A note on the max heart rate formula: the familiar 220 − Age comes from a 1971 literature
review, not an experiment, and it drifts at both ends of the age range. Tanaka’s 208 − (0.7 × Age) fits measured data better and is the default here. Both are offered above, and the result
panel shows what the other one would have given, because the honest answer is that any age-based
estimate carries about ±10 to 15 bpm of individual variation.
Heart Rate Zones:
| Zone | % of MHR | Purpose |
|---|---|---|
| Zone 1 | 50–60% | Warm-up, recovery, easy walking |
| Zone 2 | 60–70% | Fat burning, base endurance |
| Zone 3 | 70–80% | Aerobic fitness, cardio improvement |
| Zone 4 | 80–90% | Speed training, performance |
| Zone 5 | 90–100% | Maximum effort, short sprints |
Practical example: A 30-year-old with a resting heart rate of 65 bpm. MHR = 208 − (0.7 × 30) = 187. Using the Karvonen method for Zone 3 (70–80%): HRR = 187 − 65 = 122. Lower bound = (122 × 0.70) + 65 = 150 bpm. Upper bound = (122 × 0.80) + 65 = 163 bpm. So the aerobic training zone is 150–163 bpm.
Without the resting heart rate, the same person gets 131–150 bpm from plain percentage-of-max. That is a 19 bpm difference at the bottom of the zone, which is the whole reason to measure your resting pulse.
When to use this calculator: Use it to set your target heart rate for cardio workouts, running, cycling, or any aerobic exercise. Staying in the right zone helps you train efficiently without overexertion.
Tips: Most general fitness goals are best served by Zone 2 and Zone 3 training. To measure resting heart rate accurately, take it three mornings in a row and average the results. Wrist-based monitors on smartwatches are convenient but can be off by 5 to 10 bpm during intense exercise, and they lag badly at the start of an interval. A chest strap is more accurate.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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