Target Heart Rate Calculator
Find your personalized target heart rate zones for different exercise intensities using the Karvonen method, which accounts for both your age and resting heart rate. Zones range from warm-up through maximum effort.
Target heart rate is the heart rate range that produces specific training adaptations — fat burning, aerobic capacity improvement, anaerobic conditioning, or peak power. Training at the right intensity for your goal is more efficient than training too hard or too easy: too low and you don't stress the system enough to improve; too high and you burn out, risk injury, or train the wrong system.
The classic approach uses age-predicted maximum heart rate (the famous "220 minus age" rule). The Karvonen method is more individualized — it incorporates your resting heart rate to calculate heart rate reserve (HRR), then sets training zones as percentages of HRR added to your resting rate. The result accounts for the fact that two 40-year-olds with the same maximum heart rate but very different fitness levels (one with a 50 bpm resting heart rate, one with 80) should train at different absolute heart rates to produce the same training stimulus.
This calculator implements the Karvonen formula and shows your five standard training zones: Zone 1 (active recovery, 50–60% HRR), Zone 2 (aerobic base building, 60–70%), Zone 3 (aerobic endurance, 70–80%), Zone 4 (anaerobic threshold, 80–90%), and Zone 5 (maximal effort, 90–100%). Most endurance training happens in Zone 2; quality interval work happens in Zones 3–5. Use the calculator to set heart rate targets for your watch or treadmill, but remember: heart rate is one signal among many — perceived exertion, breathing rate, and pace all matter too.
Inputs
Measure first thing in the morning before getting up
Results
Max HR
190 bpm
HR Reserve
125 bpm
Fat Burn Zone
140-153
Aerobic Zone
153-165
Heart Rate Zones (Karvonen Method)
| Detail | Value |
|---|---|
| Age | 30 years |
| Resting Heart Rate | 65 bpm |
| Max Heart Rate (220 - age) | 190 bpm |
| Heart Rate Reserve | 125 bpm |
| Zone 1 - Warm Up | 128 - 140 bpm |
| Zone 2 - Fat Burn | 140 - 153 bpm |
| Zone 3 - Aerobic | 153 - 165 bpm |
| Zone 4 - Anaerobic | 165 - 178 bpm |
| Zone 5 - Max Effort | 178 - 190 bpm |
Formula
How to use this calculator
- Enter your current age. The formula uses age to estimate maximum heart rate.
- Enter your resting heart rate. Measure first thing in the morning, before getting out of bed, by counting your pulse for 60 seconds (or 30 seconds × 2). Average 2–3 morning readings for accuracy. Healthy adult RHR ranges: athletes 40–60 bpm, fit individuals 50–70 bpm, average 60–80 bpm.
- Review the five training zones with target heart rate ranges in beats per minute.
- For long endurance training (Zone 2), the target zone is the foundation of most aerobic training. Counterintuitively, this is "easier" than most beginners realize — you should be able to hold a conversation while in Zone 2.
- For interval training, the work intervals should reach Zone 4 or 5; recovery intervals drop back into Zone 1 or 2.
- For weight loss specifically: extended time in Zone 2 burns the most fat per minute (the "fat burning zone"). However, total calorie burn matters more than the fat-burning ratio — higher intensity burns more total calories per minute even if the fat percentage is lower.
- Use a heart rate monitor (chest strap is most accurate; wrist-based is convenient but ±10% off during high intensity) to know which zone you're actually in during exercise. Subjective perception is unreliable — most people overestimate their intensity.
- Re-run the calculator if your resting heart rate changes meaningfully (10+ bpm shift over weeks/months) — improvement in cardiovascular fitness typically lowers RHR, which shifts all zone calculations.
Worked examples
Beginner runner, moderate fitness
Age 35, resting heart rate 72 bpm. HRmax = 220 − 35 = 185 HRR = 185 − 72 = 113 Zone 2 (aerobic base, 60–70% HRR): 140 to 151 bpm For a beginner runner, this is the right "long slow distance" zone. Should feel comfortable, conversational. Many beginners run their easy runs too hard (155+ bpm) and end up overtrained.
Cyclist with high baseline fitness
Age 45, resting heart rate 50 bpm (well-trained). HRmax = 220 − 45 = 175 HRR = 175 − 50 = 125 Zone 4 (anaerobic threshold, 80–90%): 150 to 163 bpm For threshold training (hard but sustainable for 30–60 minutes), this rider should aim for 150–163 bpm. Lower than the equivalent zone for a less-trained person, even at the same age — because the trained athlete's resting heart rate is so much lower.
Comparing Karvonen to simple %HRmax method
Same person: age 50, resting HR 65 bpm. HRmax = 170 (220 − 50) HRR = 105 Zone 3 (aerobic endurance) by Karvonen (70–80% HRR): 138 to 149 bpm Zone 3 by simple %HRmax (70–80% HRmax): 119 to 136 bpm The Karvonen-calculated range is about 13–15 bpm higher. The simple %HRmax method would have this person running 30 minutes at 130 bpm thinking they're training Zone 3 aerobic endurance, but they're actually in Zone 1–2 active recovery range. The Karvonen method is more accurate when resting heart rate is meaningfully above or below typical.
When to use this calculator
Use this calculator when starting a structured training program, setting up heart rate alerts on a watch or treadmill, planning interval workouts, or trying to match training intensity to a specific goal.
Zone-based training is most useful for endurance athletes (runners, cyclists, triathletes, rowers) where heart rate is a reliable indicator of physiological stress. It's less useful for activities where heart rate is influenced by factors other than physical intensity (heavy resistance training, where heart rate spikes during sets but isn't the limiting factor; high-intensity intervals, where heart rate lags behind perceived intensity).
Pair this with the BMR/TDEE calculators (calorie planning), the calorie/calories-burned calculator (for exercise calorie tracking), and the pace/distance calculators for running (which integrate with heart rate planning).
A note on accuracy: the "220 minus age" formula is an average. Individual variation is large — your true HRmax could be ±15 bpm from the formula. The most accurate way to determine HRmax is a maximal test (running, biking, or rowing to true exhaustion), but this is intense and not for beginners. For most people, the formula is close enough to set training zones that produce the intended adaptation.
Heart rate also drifts upward in hot weather, during dehydration, after caffeine, and with stress — meaning the same physical effort produces a higher heart rate in those conditions. Some training plans intentionally use heart rate as a moderator (slower pace in heat is fine if heart rate is what's elevated) while others use rate of perceived exertion (RPE) as a backup. For serious athletes, knowing how to use both is more powerful than either alone.
A trend worth noting: "Zone 2 training" has had a resurgence in popularity, advocated by researchers like Dr. Peter Attia and Dr. Iñigo San Millán. The premise is that extended time in Zone 2 (often 3+ hours per week) builds mitochondrial density and metabolic flexibility better than higher-intensity training alone. Most well-rounded endurance programs combine substantial Zone 2 work with shorter, harder Zone 4–5 intervals.
Common mistakes to avoid
- Running easy days too hard. The most common mistake in distance running. "Easy" should be Zone 2 — conversational pace. Most beginners run their easy days in Zone 3, which fatigues them without producing the aerobic adaptations Zone 2 is meant to develop.
- Trusting wrist-based heart rate monitors during high intensity. Optical wrist monitors are 5–10% off during steady-state activity and can be 15%+ off during interval work due to motion artifact. Chest-strap monitors are much more accurate. For interval training, use chest strap or accept that the reading is approximate.
- Using "220 minus age" as gospel. The formula has substantial individual variation. Your actual maximum heart rate could be 15 bpm higher or lower than predicted. Adjust zones based on actual experience over weeks of training.
- Forgetting that resting heart rate changes with fitness. A previously sedentary person who becomes fit may see RHR drop from 80 bpm to 55 bpm over 6–12 months. This shifts all Karvonen zones. Recalculate periodically.
- Training in Zone 5 too often. Zone 5 work is highly stressful and slow to recover from. Most plans include 1–2 short Zone 5 sessions per week, not daily. Daily max-effort training leads to overtraining quickly.
- Ignoring heart rate variability and other recovery signals. Heart rate is one input. Heart rate variability (HRV), resting heart rate trends, sleep quality, and subjective feeling all matter. A "good zone" workout done on poor sleep can be a counterproductive stress.
Frequently Asked Questions
Sources & further reading
- Physical Activity Guidelines for Americans — U.S. Department of Health and Human Services
- Heart Rate Recommendations — official AHA guidance — American Heart Association
- Exercise and Physical Activity — research overview — U.S. Centers for Disease Control and Prevention