Target heart-rate equations and important limitations
Estimate broad moderate and vigorous exercise heart-rate ranges using age-predicted maximum heart rate, with an optional resting-heart-rate reserve method.
This page provides an equation-based estimate for education and planning. It does not diagnose a condition, measure an individual response, or replace professional care.
How to use this health calculator
- Choose appropriate inputs: Enter measurements using the units and ranges shown.
- Review the assumptions: Confirm that the model applies before interpreting the result.
- Calculate and interpret: Read the result together with its limitations and cautions.
- Use professional guidance when needed: Do not use a general calculator to change medication, treatment, or a clinician-directed plan.
Formula and variables
Moderate uses 50–70% and vigorous uses 70–85%. Both methods depend on an age-predicted maximum, so results are approximate population guides.
HRmax = 220 − age; percent-maximum target = HRmax × intensity; reserve target = resting HR + (HRmax − resting HR) × intensity- HRmax — Predicted maximum heart rate
- 220 minus age in years.
- HRrest — Resting heart rate
- Resting beats per minute used by the reserve method.
- I — Intensity fraction
- 0.50–0.70 for moderate or 0.70–0.85 for vigorous.
Worked example: age 40 using percent maximum
A 40-year-old selects the percent-maximum method.
- Age
- 40 years
- Method
- Percent maximum
- 220 − 40 = 180 bpm predicted maximum.
- Moderate: 180 × 0.50 to 180 × 0.70 = 90–126 bpm.
- Vigorous: 180 × 0.70 to 180 × 0.85 = 126–153 bpm.
Result: The estimated ranges are 90–126 bpm moderate and 126–153 bpm vigorous.
These are averages for exercise planning, not measured thresholds, a cardiac diagnosis or permission to exercise.
Understanding your results
Equation result
The numerical output follows the displayed formula and entered assumptions.
Personal interpretation
Individual biology, measurement error, environment, health conditions and medicines can change real-world outcomes.
Assumptions
- Age is entered as a whole year.
- Resting pulse, when used, is measured under genuinely resting conditions.
- The 220-minus-age approximation is suitable for a broad estimate.
Limitations
- Actual maximum heart rate varies substantially among people of the same age.
- Medication, heart rhythm, illness, heat, hydration and fitness can alter exercise heart rate.
- Wrist devices and manual pulse checks have measurement error.
- Calculated zones do not replace measured thresholds or clinician-directed cardiac rehabilitation targets.
Common mistakes
- Treating predicted maximum as a limit that must be reached.
- Using an exercise pulse as resting heart rate.
- Ignoring medicines such as beta blockers that affect heart rate.
- Continuing exercise despite concerning symptoms because the pulse is inside a calculated range.
Practical use cases
Educational estimate
Explore how the inputs affect the equation result.
Consistent tracking
Compare estimates only when methods, units and conditions are consistent.
Planning and decision guide
Treat cautions as part of the result
Start conservatively and use perceived exertion and the ability to speak alongside heart rate.
People with cardiovascular disease, symptoms, relevant medicines or clinician-directed exercise restrictions need individualized advice.
Escalate symptoms or clinical questions
Seek qualified medical advice for symptoms, diagnosed conditions, medicines, pregnancy, or individualized treatment decisions.
Frequently asked questions
Is 220 minus age exact?
No. It is a convenient population approximation and individual maximum heart rate can differ.
What is the reserve method?
It applies intensity to the difference between predicted maximum and resting heart rate, then adds resting heart rate.
Do medications affect the result?
Yes. Ask the prescribing clinician for an appropriate target.
Sources and review
- Target Heart Rates Chart — American Heart Association. Accessed 2026-08-03.
- The Effects of Training on Heart Rate: A Longitudinal Study — Annales Medicinae Experimentalis et Biologiae Fenniae (PubMed record). Accessed 2026-08-03.
Reviewed 2026-08-03.