Target Heart Rate Zones Calculator
Calculate your 5 target heart rate training zones from age and resting heart rate.
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 zone 1 low (50%) and the full breakdown beneath it.
Calculate your personalised heart-rate training zones using the Karvonen formula, which factors in your resting heart rate for greater accuracy.
⚠ This tool is for general information and education only and is not medical advice. Consult a qualified healthcare professional before making health decisions.
Formula
MHR = 220 − Age
HRR (Heart Rate Reserve) = MHR − Resting Heart Rate
Zone boundary = round(HRR × intensity%) + Resting Heart Rate
Using the Karvonen method with five zones at 50/60/70/80/90/100% of HRR.
How it works
This calculator uses the Karvonen (heart rate reserve) method, which anchors zones to both the maximum and resting heart rates rather than to MHR alone. By incorporating resting heart rate, the formula produces personalised zones that shift upward for fitter individuals who have lower resting rates.
The five zones correspond to progressively more intense effort: Zone 1 (50–60% HRR) is easy aerobic recovery; Zone 2 (60–70%) builds aerobic base; Zone 3 (70–80%) is tempo; Zone 4 (80–90%) is threshold; Zone 5 (90–100%) is maximal. MHR is estimated with the 220-minus-age formula, which carries an inherent ±10–12 bpm uncertainty.
Worked example
- Age: 30, Resting Heart Rate: 60 bpm.
- MHR = 220 − 30 = 190 bpm. HRR = 190 − 60 = 130 bpm.
- Zone 1: low = round(130×0.50)+60 = 125 bpm; high = round(130×0.60)+60 = 138 bpm.
- Zone 5: low = round(130×0.90)+60 = 177 bpm; high = round(130×1.00)+60 = 190 bpm.
Zone 1: 125–138 bpm | Zone 2: 138–151 bpm | Zone 3: 151–164 bpm | Zone 4: 164–177 bpm | Zone 5: 177–190 bpm
Common mistakes to avoid
- Measuring resting heart rate after exercise or caffeine intake rather than first thing in the morning, which inflates the resting HR and shifts all zone boundaries upward.
- Using the simpler percentage-of-MHR method (ignoring heart rate reserve) and confusing its zone numbers with the Karvonen method output — the two methods produce different BPM boundaries.
- Targeting the top of a zone rather than staying within it, particularly in Zone 2, which causes aerobic base training sessions to drift into anaerobic work.
Key terms
- Heart Rate Reserve (HRR)
- The difference between maximum and resting heart rate; it represents the functional range available for exercise intensity adjustments.
- Karvonen method
- A formula for training zones that uses heart rate reserve rather than raw MHR percentages, producing zones that adjust for individual fitness level.
- Resting Heart Rate (RHR)
- The number of heart beats per minute at complete rest, typically measured first thing in the morning; lower values generally indicate better cardiovascular fitness.
- Aerobic threshold
- Roughly the Zone 2/3 boundary (~70% HRR) where the body transitions from predominantly fat to a greater carbohydrate fuel mix.
- Lactate threshold
- Approximately the Zone 4 region (~80–90% HRR) where lactate accumulates faster than it can be cleared, limiting sustained effort.
Frequently asked questions
- What is the Karvonen formula?
- Karvonen target HR = (Max HR - Resting HR) × intensity% + Resting HR. It gives more personalised zones than simple percentage-of-max because it accounts for your cardiovascular fitness.
- Which zone is best for fat burning?
- Zone 2 (60–70% of max) is the classic fat-burning zone. Higher zones burn more total calories but use a higher proportion of carbohydrates.