This target heart rate calculator estimates a mid intensity training pulse from age and resting heart rate. It uses max HR ≈ 220 – age, then resting + 50% of heart rate reserve. The default age 30 and resting 60 returns 125 bpm.
Treat it as an educational starting point for zone talk, not a personalized prescription. For body composition context alongside training, see the BMI calculator or the calorie calculator.
How the formula works
Max = 220 – age. Reserve = max – resting. Target = resting + 0.5 × reserve. For the defaults, max = 190, reserve = 130, target = 60 + 65 = 125.
Worked example
Age 30, resting 60. Target heart rate at 50% reserve is 125 bpm.
| Input | Value |
|---|---|
| Age | 30 |
| Resting HR | 60 |
| Estimated max | 190 |
| Target (50% reserve) | 125 bpm |
How to use the fields
- Age is your age in years.
- Resting HR is beats per minute at true rest.
Heart rate reserve idea
Reserve is the gap between resting and estimated max. Training intensities are often described as percentages of that gap. This calculator locks the primary output at 50% so the number is easy to check by hand.
Common mistakes
- Measuring resting HR after coffee or a stressful commute
- Treating 220 – age as an exact personal maximum
- Using the target as a hard medical limit
- Comparing chest strap and wrist readings without noting the device
Practical use
During steady cardio, glance at a monitor and see whether you sit near 125 on the default profile or near your own recalculated target. Adjust pace if you are far above or below for the session goal you set with a coach.
Classroom practice
Have learners compute max and reserve on paper before confirming 125. Then raise resting to 70 and predict the new target before recalculating.
Discuss why two people of the same age can have different targets when resting HR differs.
Device differences
Wrist optical sensors and chest straps can disagree during intervals. Use one device consistently when you compare sessions to the calculated target.
If readings jump wildly, slow the pace and check fit before trusting a single spike.
Warmup and cooldown
The 125 bpm style target is for the working portion of a session in this educational model. Warmups sit lower, and cooldowns ease down. Do not force the target from the first step.
Write the session plan with phases so the single number is not misapplied.
When to get guidance
Heart conditions, pregnancy, and some medications change safe intensity. This calculator cannot account for those factors. Seek professional guidance before using heart rate targets as training rules in those cases.
Educational estimates are starting points for conversation, not clearance for vigorous exercise.
Talk test companion
Besides the number 125 on the default profile, many coaches still use a talk test: you should be able to speak short sentences at moderate effort. If you cannot, you may be above the intended intensity even if the watch lags.
Use heart rate and perceived effort together rather than chasing a single beep from a wearable.
Recalculate when resting HR trends down with fitness, because reserve grows and the 50 percent target shifts upward slightly.
Interval sessions
Intervals swing above and below a steady target on purpose. Use the 50 percent reserve number as an anchor for steady work, not as a ceiling during short hard repeats unless a coach says so.
Average heart rate across an interval workout can sit near the target while peaks are higher. Read the workout design before judging compliance from a single average.
Rest day resting HR
Resting HR can bounce with sleep debt and illness. If your resting number spikes for several mornings, reconsider hard sessions even if the calculated target has not changed yet.
Update the resting field when the new baseline looks stable, then recompute the target.
Limitations
No medication adjustments, no lab measured max HR, and no full multi zone chart. Educational 50% reserve estimate only.