Heart Rate Zones Calculator
Calculate your 5 training heart rate zones using the Karvonen heart-rate reserve method. Enter your age and resting heart rate for a personalised zone chart.
How to use this tool
- Enter age and resting heart rate in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your estimated max hr and the full breakdown beneath it.
Training in the right heart-rate zone maximises the adaptation you want — fat burning in Zone 2, lactate threshold work in Zone 4. The Karvonen method personalises zones using your heart-rate reserve (max HR minus resting HR).
220 minus age is an estimate. Not medical advice — consult your doctor before high-intensity exercise.
⚠ This tool is for general information and education only and is not medical advice. Consult a qualified healthcare professional before making health decisions.
Formula
Estimated Max HR = 220 − age
Heart Rate Reserve (HRR) = Max HR − Resting HR
Zone lower bound = Resting HR + HRR × lower fraction
Zone upper bound = Resting HR + HRR × upper fraction
Zone fractions: Z1 50–60%, Z2 60–70%, Z3 70–80%, Z4 80–90%, Z5 90–100%.
How it works
This tool uses the Karvonen method, which accounts for resting heart rate when setting training zones — making the zones more personalised than simple percentage-of-max-HR formulas. Max HR is estimated with the age-based formula 220 minus age, which carries a standard deviation of roughly ±10–12 bpm; individuals who know their true max HR from a lab or field test can substitute that value mentally. The five zones correspond to common athletic training classifications from recovery through anaerobic effort.
Worked example
- Age = 30, Resting HR = 60 bpm. Max HR = 220 − 30 = 190 bpm.
- Heart Rate Reserve (HRR) = 190 − 60 = 130 bpm.
- Zone 1 (50–60%): lower = 60 + 130 × 0.50 = 125 bpm; upper = 60 + 130 × 0.60 = 138 bpm.
- Zone 2 (60–70%): lower = 138 bpm; upper = 60 + 130 × 0.70 = 151 bpm.
Max HR = 190 bpm; Zone 1: 125–138 bpm; Zone 2: 138–151 bpm.
Common mistakes to avoid
- Using 220 minus age as an exact maximum HR — it is a population average with +/-10-12 bpm standard deviation, so actual max HR can shift all zone boundaries significantly.
- Measuring resting heart rate mid-day after activity rather than first thing in the morning, which overstates resting HR and compresses zone widths.
- Confusing zone number with effort level — Zone 2 in the Karvonen model (60-70% HRR) is low-effort aerobic base training, not a fat-burning sprint zone.
Key terms
- Karvonen method
- A heart rate zone formula that incorporates resting HR alongside max HR, producing zones relative to an individual's functional heart rate range rather than just their maximum.
- Heart Rate Reserve (HRR)
- The difference between maximum heart rate and resting heart rate; it represents the working range of the heart available for exercise.
- Max HR (MHR)
- The highest heart rate an individual can safely sustain; commonly estimated as 220 minus age, though actual values vary by ±10–12 bpm.
- Resting Heart Rate (RHR)
- Heart rate measured at complete rest, typically first thing in the morning before getting out of bed; lower values generally reflect better cardiovascular fitness.
- Zone 2 aerobic training
- Exercise at 60–70% of heart rate reserve, considered the primary zone for building aerobic base, fat oxidation, and cardiovascular efficiency.
Frequently asked questions
- What is the Karvonen method?
- It calculates training zones as a percentage of heart-rate reserve (max HR − resting HR), then adds resting HR. This personalises zones better than using max HR alone.
- How do I find my resting heart rate?
- Measure your pulse first thing in the morning before getting up, ideally on several days and average the results.