Calculate your 5 heart rate training zones using the Karvonen formula. Enter your age and resting heart rate for personalized zone targets.
Heart rate training zones divide your exercise intensity into five distinct ranges, each targeting different physiological adaptations. This calculator uses the Karvonen method — the gold standard personalized approach — which factors in your resting heart rate to calculate zones based on your Heart Rate Reserve (HRR).
Unlike the simpler %HRmax method, the Karvonen formula accounts for your individual fitness level through resting heart rate. A well-trained athlete with a resting HR of 50 bpm and a sedentary person with a resting HR of 80 bpm will get very different zone ranges, even if they're the same age.
Each zone has specific training benefits: Zone 1 for warm-up and recovery, Zone 2 for building aerobic base, Zone 3 for improving aerobic fitness, Zone 4 for increasing anaerobic threshold, and Zone 5 for peak performance and speed. Whether you are a beginner or experienced professional, this free online tool provides instant, reliable results without manual computation.
Training in the right heart rate zone ensures you're working at the correct intensity to achieve your fitness goals. Zone 2 training builds endurance, Zone 4 improves lactate threshold, and Zone 5 develops speed. The Karvonen method gives more accurate personalized zones than the standard %HRmax approach. Having a precise figure at your fingertips empowers better planning and more confident decisions.
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.
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.