Sports
Heart Rate Reserve Zone Calculator
Calculate heart-rate reserve, lower and upper Karvonen targets, zone width, and comparison with an age-predicted maximum. Review intensity sensitivity, measurement guidance, limitations, and FAQs.
Age-predicted maximum heart rate-
Maximum heart rate used-
Heart-rate reserve-
Lower Karvonen target-
Upper Karvonen target-
Target-zone width-
Selected maximum minus age prediction-
Lower target as share of working maximum-
Decision view
Heart-rate reserve target zone
Heart-rate reserve target zoneResting, lower-target, upper-target, and working maximum values remain explicit.
Target-zone boundaries across training intensityThe entered lower intensity changes across the exact scenarios; lower and upper Karvonen targets remain separate beats-per-minute series.
Exact scenario comparisonLower target intensity (%) changes while all other entered assumptions remain constant.
| Lower target intensity (%) | Age-predicted maximum heart rate | Maximum heart rate used | Heart-rate reserve | Lower Karvonen target | Upper Karvonen target | Target-zone width | Selected maximum minus age prediction | Lower target as share of working maximum |
|---|
Period-by-period detail
Heart-rate reserve zone reconciliation
How to use Heart Rate Reserve Zone Calculator
- Enter a stable resting heart-rate measurement.
- Enter the maximum heart rate intentionally selected for the plan.
- Choose lower and upper reserve intensities in ascending order.
- Treat the zone as a planning reference and adjust only with suitable health and training guidance.
Calculator guide
Understanding Heart Rate Reserve Zone Calculator
Heart-rate reserve zones add an intensity fraction of the difference between selected maximum and resting heart rate back to resting heart rate. This preserves the selected maximum separately from the age-predicted comparison.
Calculation method
How the calculation works
Use an explicitly selected maximum heart rate, show the Tanaka age estimate only as a comparison, then add selected fractions of heart-rate reserve to resting heart rate. Heart-rate reserve equals selected maximum minus resting heart rate. Each entered intensity percentage multiplies the reserve, then resting heart rate is added to produce the lower and upper targets.
Training use
Interpret a heart-rate zone with session context
Heart rate responds to more than mechanical workload.
Worked situations
Practical examples
- A lower resting heart rate changes reserve targets even when maximum heart rate is unchanged.
- Using an observed maximum instead of an age formula can materially shift the zone.
- Two people at the same percentage of maximum can have different reserve-based targets.
Better inputs
Useful tips
- Measure resting heart rate under consistent conditions.
- Use device readings as estimates and watch for signal artifacts.
- Consider heat, altitude, fatigue, medications, and illness before interpreting a session.
Before relying on the result
Limitations and common mistakes
- Age formulas have large individual error and an observed peak may not be a true maximum.
- The model does not provide exercise clearance or prescribe safe intensity.
- Cardiac, autonomic, medication, pregnancy, and environmental factors can change appropriate targets.
Reference
Key terms
- Resting heart rate
- Entered baseline beats per minute before exercise.
- Working maximum
- Selected maximum heart rate actually used in the zone equation.
- Heart-rate reserve
- Working maximum minus resting heart rate.
- Karvonen target
- Resting heart rate plus a selected fraction of heart-rate reserve.
Important note
Calculated from the entered performance values using the displayed method. Health, fitness, terrain, weather, equipment, and event conditions can change real-world outcomes.
Frequently asked questions
Why not use 220 minus age directly?
The page uses the entered maximum and shows an age-predicted value only for comparison.
Can the upper intensity be below the lower?
That would reverse the intended zone; enter ordered intensity percentages.
Is heart-rate reserve the same as VO2 reserve?
They can be related in some exercise contexts but are not identical measurements.
Does the result establish a safe workout?
No. Health status and individualized guidance remain necessary.