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Sports

Target Heart Rate Zone Calculator.

Calculates your target heart rate zone (50-85% of max) based on age and resting heart rate, using the Karvonen formula.

Results update live as you type.
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Your inputs

How it works

  1. 1

    Enter your age and resting heart rate.

  2. 2

    The calculator estimates your maximum heart rate as 220 minus age.

  3. 3

    It subtracts your resting heart rate to find your heart rate reserve.

  4. 4

    It multiplies the reserve by the intensity percentage and adds back your resting heart rate.

round((((220 - age) - resting_hr) * 0.7) + resting_hr)

Frequently asked questions

What is the Karvonen formula?

It calculates target heart rate using your heart rate reserve (max HR minus resting HR) and an intensity percentage, then adds resting HR back.

Why use resting heart rate?

Resting heart rate personalizes the zone, making it more accurate than a simple percentage of max heart rate.

What intensity should I use?

Moderate exercise is typically 50-70% of your heart rate reserve; vigorous is 70-85%. Consult a professional for medical advice.

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Results

Formula checked

Target Heart Rate (70% intensity)

151bpm

Lower bound (50%)125bpm
Upper bound (85%)171bpm
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Estimate for general guidance only — verify important decisions with an appropriate professional.

How it works

Calculates your target heart rate zone (50-85% of max) based on age and resting heart rate, using the Karvonen formula.

  1. Enter your age and resting heart rate.
  2. The calculator estimates your maximum heart rate as 220 minus age.
  3. It subtracts your resting heart rate to find your heart rate reserve.
  4. It multiplies the reserve by the intensity percentage and adds back your resting heart rate.

Formulas

The math behind this calculator, written out so you can verify the result.

Karvonen Formula

Target HR = ((Max HR - Resting HR) × Intensity) + Resting HR

Max HR is estimated as 220 minus age. The difference between max and resting HR is your heart rate reserve, which is multiplied by the desired intensity fraction.

Real-world use cases

Where this calculation shows up in everyday life.

Cardio Training

Find the right intensity for endurance or interval workouts.

Example: A runner uses 70-80% for tempo runs.

Fitness Tracking

Monitor if you're exercising in the desired zone.

Example: Check your heart rate during a workout.

Rehabilitation

Stay within a safe range after injury or illness.

Example: A physiotherapist prescribes 50-60% for recovery.

Tips and common mistakes

Tips

  • Measure your resting heart rate in the morning before getting up.
  • Use a heart rate monitor for accuracy during exercise.
  • Adjust intensity based on how you feel, not just numbers.
  • Recheck your resting heart rate periodically as fitness improves.

Common Mistakes to Avoid

  • Using 220 minus age without accounting for resting heart rate.
  • Setting intensity too high for beginners.
  • Ignoring medications or conditions that affect heart rate.

Assumptions and limitations

  • Use the stated inputs and units.
  • Results are estimates for planning and education.
  • Check measurements and source data before making an important decision.