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Target Heart Rate Zones Calculator

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

Solution

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How It Works

Target heart rate zones partition your heart rate reserve into five training bands keyed to physiological adaptations. Each zone is a percentage range of heart rate reserve (HRR = HRmax − HRrest) applied to the Karvonen formula THR = HRR × intensity + HRrest. The five zones — Active Recovery (50–60%), Aerobic / Endurance (60–70%), Tempo (70–80%), Lactate Threshold (80–90%), and VO2max (90–100%) — give a structured way to prescribe workouts. Enter your maximum and resting heart rates and the calculator returns the bpm range for each zone.

Example Problem

An athlete with HRmax 190 bpm and resting HR 60 bpm wants the five Karvonen training zones.

  1. Compute heart rate reserve: HRR = 190 − 60 = 130 bpm.
  2. Zone 1 (50–60%): 50% → 65 + 60 = 125 bpm, 60% → 78 + 60 = 138 bpm. Range ≈ 125–138 bpm.
  3. Zone 2 (60–70%): 60% → 138 bpm, 70% → 91 + 60 = 151 bpm. Range ≈ 138–151 bpm.
  4. Zone 3 (70–80%): 151–164 bpm.
  5. Zone 4 (80–90%): 164–177 bpm.
  6. Zone 5 (90–100%): 177–190 bpm (caps at HRmax).

Key Concepts

Zone-based training derives from research on the physiological responses to different exercise intensities. Aerobic Zone 2 builds mitochondrial density and fat-burning capacity; Tempo Zone 3 raises lactate threshold; Threshold Zone 4 trains sustainable race-pace power; VO2max Zone 5 develops peak oxygen-uptake capacity. Most endurance programs follow an 80/20 distribution: about 80% of training volume in Zones 1–2 and 20% in Zones 4–5, with Zone 3 used sparingly. Coggan-style power zones, Friel-style heart-rate zones, and the simpler 5-zone HRR model all map onto the same physiological continuum.

Applications

  • Structuring a weekly endurance training plan (long easy runs in Zone 2, intervals in Zone 4–5).
  • Programming heart-rate alerts on Garmin, Polar, Suunto, Apple Watch, and Wahoo devices.
  • Pacing road races: marathons in Zone 2–3, half marathons in Zone 3–4, 5K in Zone 4–5.
  • Monitoring cardiac rehabilitation patients within physician-prescribed zone ceilings.
  • Tracking polarized vs. threshold training distributions across a training block.

Common Mistakes

  • Spending too much time in Zone 3 ("the grey zone"). Easy effort should be truly easy (Zone 2) and hard effort should be truly hard (Zone 4–5).
  • Using a single max HR estimate as if it were precise. The ±12 bpm uncertainty in 220 − age shifts every zone boundary by 5–10 bpm.
  • Forgetting that heart rate lags effort. On short intervals, RPE and power can be better intensity guides than instantaneous HR.
  • Comparing your zones to someone else's. Zones are personal — they're scaled to your HRmax and HRrest, both of which vary widely.
  • Ignoring heat, altitude, sleep, and stress. HR runs higher in heat and after poor sleep, so the same effort lands in a higher zone.

Frequently Asked Questions

How do you calculate target heart rate zones?

Apply the Karvonen formula to each zone's intensity range. For Zone 2 (60–70% of heart rate reserve): low = (HRmax − HRrest) × 0.60 + HRrest, high = (HRmax − HRrest) × 0.70 + HRrest. Repeat for each zone's intensity boundaries.

What are the 5 heart rate training zones?

Zone 1 (50–60% HRR, active recovery), Zone 2 (60–70% HRR, aerobic / endurance), Zone 3 (70–80% HRR, tempo), Zone 4 (80–90% HRR, lactate threshold), and Zone 5 (90–100% HRR, VO2max intervals). Each zone targets a different physiological adaptation.

What is Zone 2 training?

Zone 2 is steady aerobic effort at 60–70% of heart rate reserve, conversational pace. It builds mitochondrial density, fat oxidation, and capillary supply — the foundation of endurance performance. Most endurance programs assign 60–80% of weekly training volume to Zone 2.

What zone should I train in to lose weight?

Long Zone 2 sessions build aerobic capacity and use a high percentage of fat for fuel. Higher-intensity Zone 4–5 intervals burn more total calories per minute. A mix of long Zone 2 work and shorter Zone 4 intervals usually outperforms staying in one zone.

What's the difference between %HRmax zones and Karvonen zones?

Percent-of-HRmax zones (e.g., 60–70% of 190 = 114–133 bpm) ignore resting HR. Karvonen zones use heart rate reserve and add resting HR back, producing personalized targets. For a fit athlete with low RHR, the difference can be 10–20 bpm in the same zone label.

How accurate are heart rate zones?

Zones are as accurate as their HRmax input. Using an estimated HRmax (220 − age, etc.) introduces ±12 bpm of population scatter. A measured HRmax from a graded exercise test makes zones much more precise. Even with measured values, day-to-day HR variability of ±5 bpm is normal.

Worked Examples

30-Year-Old, Average Fitness

What are the five training zones for HRmax 190, HRrest 60?

  • Heart rate reserve: HRR = 190 − 60 = 130 bpm
  • Zone 1 (50–60%): ≈ 125–138 bpm
  • Zone 2 (60–70%): ≈ 138–151 bpm
  • Zone 3 (70–80%): ≈ 151–164 bpm
  • Zone 4 (80–90%): ≈ 164–177 bpm
  • Zone 5 (90–100%): ≈ 177–190 bpm

Long easy runs land in Zones 1–2; intervals push into Zone 4–5.

Trained Athlete, Low Resting HR

How do zones shift for an athlete with HRmax 180, HRrest 45?

  • HRR = 180 − 45 = 135 bpm
  • Zone 2 (60–70%): 0.60 × 135 + 45 to 0.70 × 135 + 45
  • Zone 2 ≈ 126–140 bpm
  • Zone 4 (80–90%): ≈ 153–167 bpm

Lower resting HR shifts the lower zone bounds down; Karvonen scales the spread by fitness.

Older Adult, Moderate Fitness

What zones apply to a 60-year-old with HRmax 160, HRrest 70?

  • HRR = 160 − 70 = 90 bpm
  • Zone 1 (50–60%): ≈ 115–124 bpm
  • Zone 2 (60–70%): ≈ 124–133 bpm
  • Zone 4 (80–90%): ≈ 142–151 bpm

Older adults should clear high-intensity work with a clinician — Zone 4–5 may be inappropriate.

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