Heart Rate Zone Calculator
Find your optimal training zones for fat burn, cardio, and peak performance. Choose simple or Karvonen method with resting heart rate.
How to use Heart Rate Zone Calculator
The heart rate zones calculator computes your five training zones from your maximum heart rate (MHR) or using the Karvonen method which also accounts for resting heart rate. Zone 1 (50–60% MHR) is recovery; Zone 2 (60–70%) burns fat and builds aerobic base; Zone 3 (70–80%) improves cardiovascular efficiency; Zone 4 (80–90%) boosts lactate threshold; Zone 5 (90–100%) builds peak power. Knowing your zones prevents overtraining and under-training.
- Choose Simple (% of MHR) or Karvonen method (requires resting heart rate).
- Enter your age — MHR is auto-estimated as 220 − age.
- Optionally override MHR with a measured value from a recent maximal-effort test.
- For Karvonen, enter your resting heart rate (measure first thing in the morning).
- Review your five zones with bpm ranges, purpose and recommended session duration.
Your data never leaves your device — 100% private processing.
Simple % MHR vs Karvonen formula
The simple method sets zones as fixed percentages of MHR: accurate enough for most recreational athletes. The Karvonen (heart rate reserve) method factors in resting heart rate: Target HR = Resting HR + (HRR × intensity%). Since a lower resting HR means a higher heart rate reserve, the Karvonen formula gives higher absolute zone values for fit athletes — more accurately reflecting true physiological effort.
Training effect of each zone
Zone 2 training (fat-burn) is the foundation of aerobic fitness — elite endurance athletes spend 70–80% of training volume here. Zone 3 stimulates mitochondrial density improvements. Zone 4 raises the lactate threshold, the primary determinant of race pace. Zone 5 sessions are short and high-stress; over-relying on them without Zone 2 base leads to overtraining. The optimal training mix depends on your sport and fitness phase.
| Zone | Name | % MHR | Primary benefit | Typical session |
|---|---|---|---|---|
| 1 | Recovery | 50–60% | Active recovery, blood flow | Easy walk or spin, 30–60 min |
| 2 | Fat Burn | 60–70% | Aerobic base, fat oxidation | Long slow runs, 45–90 min |
| 3 | Cardio | 70–80% | Cardiovascular efficiency | Steady-state effort, 20–45 min |
| 4 | Threshold | 80–90% | Lactate threshold | Tempo runs, 10–30 min |
| 5 | Anaerobic | 90–100% | Peak power output | Intervals, 2–10 min |
Glossary
- MHR
- Maximum Heart Rate — the highest heart rate achievable during maximal effort exercise.
- HRR
- Heart Rate Reserve — the difference between MHR and resting heart rate.
- Karvonen
- A heart rate zone formula that uses HRR to set more personalised training targets.
- Lactate threshold
- The exercise intensity at which blood lactate begins accumulating faster than it can be cleared.
Related reading
Frequently Asked Questions
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Why use Heart Rate Zone Calculator?
- Based on widely-accepted clinical and scientific formulas
- No personal data stored — all calculations run locally
- Supports both metric and imperial units
- Results include actionable recommendations
Common use cases
- Calculate BMI before a doctor's appointment
- Estimate daily calorie needs for a weight loss goal
- Track ideal body weight range for a fitness plan
- Calculate pregnancy due date
- Find out your recommended water intake based on body weight
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