Calculate your 5 heart rate training zones using the Karvonen formula. Enter your age and resting heart rate for personalized zone targets.
Heart rate zones divide exercise intensity into ranges linked to different training purposes.
This calculator uses the Karvonen method, which incorporates resting heart rate through heart-rate reserve instead of relying only on maximum heart rate. That usually gives a more individualized starting point than simple %HRmax zones.
The five-zone layout is a practical way to organize easier aerobic work, threshold sessions, and harder efforts.
It is useful for setting training ranges when you monitor heart rate during exercise. The zones are still estimates, especially if maximum heart rate is age-predicted rather than measured directly.
Heart Rate Reserve (HRR) = HRmax − HRrest Target HR = (HRR × %intensity) + HRrest Karvonen Zones: • Zone 1 (Recovery): 50–60% HRR • Zone 2 (Aerobic): 60–70% HRR • Zone 3 (Tempo): 70–80% HRR • Zone 4 (Threshold): 80–90% HRR • Zone 5 (VO₂max): 90–100% HRR Default HRmax = 220 − age
Result: Zone 2: 135–148 bpm | Zone 4: 160–173 bpm
For a 35-year-old with resting HR of 60: HRmax = 220 − 35 = 185 bpm. HRR = 185 − 60 = 125 bpm. Zone 2 (60–70% HRR): (125 × 0.60) + 60 = 135 bpm to (125 × 0.70) + 60 = 148 bpm. Zone 4 (80–90% HRR): (125 × 0.80) + 60 = 160 bpm to (125 × 0.90) + 60 = 173 bpm.
Zone 1 (50–60% HRR) is the warm-up and recovery zone. It's used for active recovery days and warm-up/cool-down. Zone 2 (60–70% HRR) is the aerobic base zone where fat oxidation peaks and mitochondria multiply. Zone 3 (70–80% HRR) is the tempo zone that improves aerobic capacity but sits in a “gray zone” that many coaches recommend avoiding. Zone 4 (80–90% HRR) is the lactate threshold zone where your body begins accumulating lactic acid faster than it can clear it. Zone 5 (90–100% HRR) is the VO₂max zone for maximum cardiovascular output.
Research consistently shows that the most effective endurance training follows a polarized distribution: 80% of training in Zones 1–2 and 20% in Zones 4–5, largely avoiding Zone 3. This approach has been validated in runners, cyclists, rowers, and cross-country skiers at both elite and recreational levels.
During sustained exercise, heart rate gradually increases even at a constant pace — a phenomenon called cardiac drift. This is caused by dehydration, rising core temperature, and reduced stroke volume. Allow for a 5–10 bpm drift in Zone 2 sessions lasting over 60 minutes.
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This worksheet estimates a maximum heart rate, subtracts resting heart rate to produce heart-rate reserve, and then applies the Karvonen formula to calculate five training zones. If a known measured HRmax is entered, the calculator uses that value instead of the age-predicted default.
The result is a training-planning estimate, not a laboratory exercise test. Day-to-day heart rate, medication effects, heat, hydration, and the accuracy of the entered HRmax all influence how useful the zones will be in practice.
The Karvonen method (also called Heart Rate Reserve method) was developed by Finnish physiologist Martti Karvonen. It calculates target heart rates using HRR = HRmax − HRrest. This is more personalized than the %HRmax method because it accounts for your resting heart rate, which reflects fitness level. Two people of the same age but different fitness levels get different zone ranges.
Resting heart rate reflects your cardiovascular fitness. A lower resting HR (50–60 bpm in fit individuals) means your heart pumps more blood per beat, requiring fewer beats at rest. The Karvonen formula uses this to personalize your zones. A person with RHR 50 has a wider effective range than someone with RHR 80, even at the same age.
Zone 2 (60–70% HRR) is the aerobic base zone where your body primarily burns fat for fuel and builds mitochondrial density. It's comfortable enough to hold a conversation. Elite endurance athletes spend 75–80% of their training here. It's popular because it builds the aerobic engine that supports all higher-intensity work without excessive recovery demands.
The 220 − age formula has a standard deviation of ±10–12 bpm, meaning it can over- or underestimate your max HR significantly. It's a rough estimate suitable for general fitness. For serious training, consider a lab-based max HR test or field test (e.g., 3-minute all-out effort on a bike, or a graded treadmill protocol).
No. Zone 5 training is extremely demanding and requires significant recovery time (48–72 hours). Training in Zone 5 daily leads to overtraining, elevated cortisol, sleep disruption, and injury risk. Most coaches recommend Zone 5 work only 1–2 times per week, with the majority of training in Zones 1–2.
The %HRmax method simply takes percentages of your max heart rate (e.g., 70% of 185 = 130 bpm). The Karvonen method uses Heart Rate Reserve, which accounts for resting HR. For someone with low resting HR, Karvonen zones are higher than %HRmax zones at the same percentages. Karvonen is generally considered more accurate for personalized training.
Recheck your resting HR every 4–8 weeks during a training program. As your fitness improves, your resting HR typically decreases, which shifts your training zones slightly. This recalibration ensures your zones remain accurate and your training stimulus stays appropriate for your current fitness level.