Determine your five heart rate training zones based on your age and resting heart rate using the Karvonen method. Each zone targets different fitness benefits from fat burning to maximum performance.
Heart rate zone training organizes exercise intensity into five (sometimes seven) bands based on percentage of maximum heart rate, with each zone targeting different physiological adaptations. Zone 1 (50-60%) is recovery; Zone 2 (60-70%) builds aerobic base and mitochondrial density; Zone 3 (70-80%) develops cardiovascular fitness and lactate clearance; Zone 4 (80-90%) raises lactate threshold and competitive race pace; Zone 5 (90-100%) is maximal effort for VO2 max development. The framework, refined by exercise scientists over decades, provides a structured way to ensure training delivers the specific adaptations you're targeting.
The Karvonen method (developed by Finnish physiologist Martti Karvonen in the 1950s) calculates zones using Heart Rate Reserve (max HR minus resting HR) rather than just max HR percentage. This personalizes the zones based on individual fitness — a 30-year-old with resting HR 50 (very fit) has different zone boundaries than a 30-year-old with resting HR 80 (average fitness), even though their max HR estimates are identical. The Karvonen formula: Target HR = (Max HR − Resting HR) × Intensity% + Resting HR. This produces more accurate zones for individual training prescription than max-HR-only calculations.
This calculator computes all five Karvonen-based zones from your age and resting heart rate. Use it for: structuring cardio training across appropriate intensity zones, ensuring most easy aerobic work happens at truly easy intensity (a common mistake — going too hard on easy days, too easy on hard days), and prescribing specific zones for endurance training, lactate threshold work, or VO2 max intervals. Important context: max HR estimation formulas have ±10-15 bpm individual variation, and zones are guides not absolute boundaries. Effort perception (RPE), pace, and power are additional intensity gauges that complement heart rate. For serious training, periodic field tests or lab testing can refine your personal zone boundaries.
Age 35, resting HR 72 (typical for sedentary adult starting exercise). Max HR (Tanaka): 208 − (0.7 × 35) = 184 HRR: 184 − 72 = 112 Zone 1 (recovery): 128-139 bpm Zone 2 (aerobic base): 139-150 bpm Zone 3 (tempo): 150-162 bpm Zone 4 (threshold): 162-173 bpm Zone 5 (max): 173-184 bpm For couch-to-5K runner: most running should be at Zone 2 boundary (~145 bpm) — conversational pace, feels almost too easy. Beginners commonly go too hard, sustaining Zone 3-4 by accident, which leads to fatigue and burnout. Slow down — most progress comes from Zone 2 time. As fitness improves: resting HR will drop (over 3-6 months, possibly to 60-65), zones will shift downward, and the same pace will produce lower heart rate. Re-measure quarterly.
Age 40, resting HR 50 (fit endurance athlete). Max HR: 208 − (0.7 × 40) = 180 HRR: 180 − 50 = 130 Zone 2: 128-141 bpm (aerobic base — long rides) Zone 4: 154-167 bpm (lactate threshold — interval work) Weekly plan (10 hours total): 6 hours Zone 1-2 (easy rides, recovery) 2 hours Zone 2 specifically (steady aerobic — long ride) 1 hour Zone 4 (threshold intervals, e.g., 4 × 8 min at Zone 4) 1 hour Zone 5 (VO2 max intervals, e.g., 5 × 3 min at Zone 5) Total: 80% easy/aerobic, 20% hard. Classic polarized distribution. Produces best endurance adaptations while preserving recovery for hard sessions.
Comparing same training intensity at different ages, similar fitness: Age 25, RHR 55: Max HR 191, Zone 2 145-150 bpm Age 45, RHR 55: Max HR 177, Zone 2 134-138 bpm Age 65, RHR 55: Max HR 162, Zone 2 119-122 bpm Older athletes train at lower absolute heart rates for same relative intensity. This is normal and expected — maximum heart rate declines about 0.7-1.0 bpm per year regardless of fitness level. Implication: don't compare absolute heart rates across ages. A 60-year-old at 130 bpm may be working as hard as a 25-year-old at 160 bpm. Zone-based prescription (rather than absolute HR targets) prevents this confusion. For older athletes: training adaptations still occur normally (improvements in VO2 max, lactate threshold, etc.). The absolute numbers are lower but the relative response is preserved.
Use this calculator when starting a structured cardio training program, periodizing endurance training, ensuring easy days are easy enough (a common training error), or learning the heart-rate-based intensity framework.
Pair with vo2-max (cardio fitness assessment), calories-burned (energy expenditure), and pace-calculator (running-specific pace).
Important heart rate training considerations:
1. **Max HR formulas have ±10-15 bpm individual variation.** Tanaka (208 − 0.7 × age) is most accurate population-average but you may be higher or lower. Field test if you want personalized accuracy.
2. **Zone 2 is foundational.** 70-80% of training time for endurance athletes. Builds aerobic base, mitochondrial density, fat oxidation. Many recreational athletes spend too little time in true Zone 2 and too much in Zone 3.
3. **Polarized training (80/20 easy/hard) produces best endurance results.** Elite athletes confirm this — spend most time genuinely easy, minimal time genuinely hard. Skip the muddled middle (Zone 3).
4. **Heart rate lags effort by 30-60 seconds.** Don't over-react to brief spikes during intervals. Average heart rate over 1-2 minutes is more meaningful than instantaneous readings.
5. **Cardiac drift on long efforts.** Heart rate rises 5-10% during long efforts at constant pace/power (due to dehydration, thermal stress). Expected normal — don't slow down dramatically to compensate; use pace/power as backup intensity gauge.
6. **Resting HR responds to training and stress.** Drops 5-15 bpm over 3-6 months of regular cardio training. Also affected by sleep, dehydration, illness, alcohol, caffeine. Multi-morning average is more reliable than single measurement.
7. **Chest strap vs. wrist monitor accuracy.** Chest strap (Polar, Garmin H10, Wahoo) is more accurate than wrist for high-intensity work. Wrist monitors (Apple Watch, Fitbit, Garmin watches) are improving but still show errors during intense intervals.
8. **Effort perception (RPE) complements heart rate.** RPE 6-7 scale (light, somewhat hard, hard, very hard) is also valuable. Heart rate + RPE + pace/power = best intensity calibration.
9. **Maximum heart rate is genetic.** Highly trained individuals don't have higher max HR than untrained — they have lower resting HR (larger HRR). Don't try to "raise" max HR; train to lower resting and improve cardiac output.
10. **Lactate threshold ≠ max HR percentage.** Threshold occurs at ~85-90% of HRR for fit individuals, ~75-80% for sedentary. Highly individual; zone-based prescription handles this approximately.
11. **Medications affect heart rate.** Beta blockers lower max HR and blunt response. Other medications (asthma inhalers, stimulants) can elevate. Discuss training with cardiologist if on heart medications.
12. **Train mostly easy, race hard.** Common training adage. Save your hardest efforts for races and key sessions. Daily training should mostly be sustainable, repeatable, easy aerobic work.
Estimate your VO2 max from running test data.
Estimate calories burned by activity and duration using MET values.
Convert between pace, time, and distance for running and walking.
Calculate your one-rep max from weight and reps using Brzycki and Epley formulas.
Calculate calories burned while walking based on speed, weight, and duration.
Max Heart Rate
190 bpm
Heart Rate Reserve
125 bpm
Fat Burn Zone
140-153 bpm
Aerobic Zone
153-165 bpm
| Zone | Name | Min HR | Max HR | Purpose |
|---|---|---|---|---|
| 1 | Recovery | 128 | 140 | Warm-up, cool-down, recovery |
| 2 | Fat Burn | 140 | 153 | Aerobic base, fat burning |
| 3 | Aerobic | 153 | 165 | Cardiovascular endurance |
| 4 | Threshold | 165 | 178 | Lactate threshold, speed |
| 5 | Maximum | 178 | 190 | Max effort, short intervals |