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Karvonen Heart Rate Calculator

Target heart rate equals (max HR minus resting HR) times intensity plus resting HR

Solution

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How It Works

The Karvonen method (sometimes called the Heart Rate Reserve method) computes a target heart rate that accounts for both maximum and resting heart rate. The formula is THR = (HRmax − HRrest) × intensity + HRrest, where intensity is a fraction between 0 and 1 (or a percent between 0 and 100). The term (HRmax − HRrest) is heart rate reserve (HRR) — the usable training range. Because the formula adds HRrest back, two people with the same HRmax but different resting rates land on different target zones, reflecting their individual cardiovascular fitness.

Example Problem

A 30-year-old with HRmax 190 bpm and resting HR 60 bpm wants the Karvonen target at 70% intensity.

  1. Compute heart rate reserve: HRR = 190 − 60 = 130 bpm.
  2. Apply intensity: 130 × 0.70 = 91 bpm.
  3. Add resting HR back: 91 + 60 = 151 bpm.
  4. Target heart rate at 70% intensity ≈ 151 bpm.
  5. For a steady aerobic effort, aim to keep your monitored HR within about ±5 bpm of this target.

Key Concepts

Karvonen (1957) introduced this method because simple percent-of-HRmax under-prescribes intensity for fit individuals with low resting heart rates. Heart rate reserve respects the fact that a marathon runner with HRrest = 45 bpm and a sedentary adult with HRrest = 80 bpm should not be assigned the same target HR for the same effort level. The American College of Sports Medicine and most cardiac rehabilitation guidelines use HRR-based prescriptions for moderate-to-vigorous intensity. Typical zones: 50–60% for active recovery, 60–70% for aerobic base building, 70–80% for tempo, 80–90% for threshold, and 90%+ for VO2max intervals.

Applications

  • Setting personalized aerobic, tempo, threshold, and VO2max zones for endurance training.
  • Prescribing safe exercise intensity in cardiac rehabilitation and pulmonary rehab.
  • Programming heart-rate monitors and smartwatches with zones that respect resting HR.
  • Comparing training load across athletes with different fitness levels using the same intensity scale.
  • Adjusting workout intensity over a training block as resting HR drops with improved fitness.

Common Mistakes

  • Using percent of HRmax instead of Karvonen — simple percent-of-max ignores resting HR and under-shoots true effort for fit individuals.
  • Measuring resting HR after coffee, stress, or while standing. Take RHR first thing in the morning before getting out of bed.
  • Using an estimated HRmax (220 − age) with a measured RHR, then treating the target as exact. The ±12 bpm uncertainty in HRmax propagates into the target.
  • Forgetting that intensity is a fraction (0.70) or a percent (70%) — entering 7 or 0.7 in a field that expects a 0–100 value yields a wildly wrong target.
  • Sticking to one target over months. As fitness improves, resting HR drops and the same intensity percentage delivers a slightly higher target — recompute periodically.

Frequently Asked Questions

How do you calculate Karvonen heart rate?

Use the formula THR = (HRmax − HRrest) × intensity + HRrest. Multiply heart rate reserve by the target intensity (as a fraction), then add resting heart rate back. For example, with HRmax = 190, HRrest = 60, and 70% intensity, THR = (190 − 60) × 0.70 + 60 = 151 bpm.

What is the formula for the Karvonen method?

THR = (HRmax − HRrest) × intensity + HRrest, where (HRmax − HRrest) is heart rate reserve and intensity is a decimal between 0 and 1. It's also called the heart rate reserve method.

What is heart rate reserve?

Heart rate reserve (HRR) is the difference between maximum and resting heart rates: HRR = HRmax − HRrest. It represents your usable training range — the bpm between rest and all-out exertion. Karvonen-based zones scale this range by the target intensity percentage.

Why use Karvonen instead of percent of max HR?

Karvonen accounts for resting heart rate, which varies a lot between individuals (40–50 bpm in trained athletes, 60–80 bpm in sedentary adults). Simple percent-of-HRmax assigns the same target to people with very different fitness levels and tends to under-prescribe intensity for fit individuals.

What is a good Karvonen intensity for fat burning?

Roughly 60–70% of heart rate reserve falls in the moderate aerobic range often called the fat-burning zone. While a higher fraction of calories at lower intensities comes from fat, higher-intensity sessions burn more total calories and fat per workout, so most training plans mix both.

How do I measure my resting heart rate?

Lie still in bed first thing in the morning before getting up. Count your pulse for 60 seconds (or 30 seconds × 2). Average several mornings to smooth out day-to-day variation. Avoid caffeine, alcohol, and stress before measuring.

Worked Examples

Recreational Runner, 70% Effort

What's the Karvonen target for a runner with HRmax 190 and resting HR 60 at 70% intensity?

  • THR = (HRmax − HRrest) × intensity + HRrest
  • THR = (190 − 60) × 0.70 + 60
  • THR = 130 × 0.70 + 60
  • THR = 91 + 60
  • THR = 151 bpm

Aerobic base building — should feel conversational but steady.

Trained Athlete, Threshold Effort

What about a trained athlete with HRmax 180, resting HR 45 at 85% intensity?

  • HRR = 180 − 45 = 135 bpm
  • THR = 135 × 0.85 + 45
  • THR = 114.75 + 45
  • THR = ≈ 160 bpm

Lactate threshold — sustainable for ~30–60 minutes.

Cardiac Rehab, Moderate Intensity

What's a safe Karvonen target for a 60-year-old in cardiac rehab at 60%?

  • HRmax ≈ 220 − 60 = 160 bpm
  • HRR = 160 − 70 = 90 bpm
  • THR = 90 × 0.60 + 70
  • THR = 54 + 70
  • THR = 124 bpm

Verify with your cardiologist — exercise prescription in cardiac rehab is individualized.

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