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Zone 2 Heart Rate Calculator

Zone 2 is the aerobic base training zone where mitochondrial volume, fat oxidation, and lactate clearance adapt most efficiently. At Zone 2 intensity you can hold a conversation, breathe through your nose, and keep blood lactate at or below about 2 mmol/L. This calculator returns a Zone 2 heart rate band using three evidence-cited methods so you can pick the approach that fits your training context.

Reviewed by GetHealthyCalculators Editorial Team · Updated April 14, 2026

Quick Answer

Zone 2 is roughly 60–70 percent of heart rate reserve (Karvonen), or within 10 bpm below the Maffetone 180 − age number. At Zone 2 effort, nasal breathing is sustainable and conversation stays comfortable. Sessions of 30–90 minutes, 2–4 times per week, are typical for aerobic base work.

These results are estimates based on general formulas and are not a substitute for professional medical advice. Consult a healthcare provider before making health decisions.

Method

Enter your age (and resting heart rate for Karvonen) to calculate your Zone 2 aerobic band.

How the Formula Works

  1. Estimate HRmax using Tanaka 2001: HRmax = 208 − 0.7 × age (more accurate than 220 − age for adults).

    HRmax = 208 - 0.7 x age

  2. Maffetone method: subtract age from 180 for a 10-bpm Zone 2 band ending at (180 − age).

    MAF Zone 2 = (180 - age - 10) to (180 - age)

  3. Karvonen method: use heart rate reserve (HRmax − RHR) and target 60–70 percent of reserve.

    Zone 2 = RHR + 0.6 x HRR to RHR + 0.7 x HRR

  4. Percent HRmax method: target 60–70 percent of age-predicted HRmax.

    Zone 2 = 0.6 x HRmax to 0.7 x HRmax

Methodology & Sources

Reviewed and updated April 14, 2026 · Prepared by GetHealthyCalculators Editorial Team

Outputs are calculated using the Tanaka age-predicted HRmax and published Zone 2 conventions. This is an educational tool; it is not a substitute for a graded exercise test with lactate or gas exchange analysis, which remain the gold standard for defining aerobic zones.

References

  • Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. (2001) · Journal of the American College of Cardiology
  • Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate. (1957) · Annales Medicinae Experimentalis et Biologiae Fenniae
  • San-Millán I, Brooks GA. Assessment of Metabolic Flexibility. (2018) · Sports Medicine
  • Maffetone P. The 180 Formula: Heart-Rate Monitoring for Real Aerobic Training. · Philmaffetone.com

Limitations

  • Age-predicted HRmax has a standard deviation of about 10 bpm — individual max heart rate varies widely.
  • Medications such as beta blockers, cardiac conditions, and poor sleep can shift Zone 2 heart rate.
  • Altitude, heat, caffeine, and hydration meaningfully change heart rate at a given effort.
  • True Zone 2 is defined by blood lactate (~1.5–2 mmol/L) — heart rate formulas are a reasonable but imperfect proxy.

Frequently Asked Questions

Why is Zone 2 specifically useful?
Zone 2 training increases mitochondrial density, fat oxidation, and lactate clearance. These adaptations underlie both long-term endurance performance and metabolic health markers like insulin sensitivity. Unlike high-intensity work, Zone 2 accumulates with minimal neuromuscular fatigue so the volume can stay high week over week.
How long should a Zone 2 session be?
Most endurance coaches target 30–90 minutes per session. Beginners can start with 20–30 minutes and build. Elite endurance athletes routinely do multi-hour Zone 2 sessions as the majority of their weekly volume.
What does Zone 2 feel like?
Nasal breathing is sustainable the whole session. A full sentence is comfortable, but holding a conversation takes a little more effort than normal. Perceived effort is about 3–4 out of 10. If you cannot talk or your breathing becomes mouth-dominant, you are drifting into Zone 3.
What activities work well for Zone 2?
Cycling, rowing, swimming, hiking, and running at an easy pace are common. Incline walking is great for anyone who cannot easily stay in Zone 2 at a jog — it raises heart rate predictably without the mechanical stress of running.
Is Zone 2 the same as the “fat-burning zone”?
They overlap. The fat-burning zone typically refers to the absolute fat-oxidation peak, which sits within Zone 2 for most untrained adults. Over time, trained individuals push peak fat oxidation higher, so the heart rate associated with Zone 2 can creep up as fitness improves.

See the full 5-zone heart rate breakdown to plan your whole week

Heart Rate Zone Calculator

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