All 5 training zones with Z2 guidance
Last reviewed: May 2026
A heart rate zone calculator determines your five training zones based on your maximum heart rate (MHR) or heart rate reserve (HRR). Training in different zones produces different physiological adaptations: Zone 1 builds aerobic base, Zone 2 maximizes fat oxidation, Zone 3 improves aerobic capacity, Zone 4 raises lactate threshold, and Zone 5 develops anaerobic power. Knowing your zones allows you to train at the right intensity for your goal — whether that's fat loss, endurance, race performance, or cardiovascular health.1
| Zone | % of Max HR | Feel | Training Effect | Example (Max HR 190) |
|---|---|---|---|---|
| Zone 1 (Recovery) | 50–60% | Very easy | Active recovery, warm-up | 95–114 bpm |
| Zone 2 (Aerobic) | 60–70% | Conversational | Fat burning, base endurance | 114–133 bpm |
| Zone 3 (Tempo) | 70–80% | Moderate effort | Aerobic capacity, stamina | 133–152 bpm |
| Zone 4 (Threshold) | 80–90% | Hard, labored breathing | Lactate threshold, speed | 152–171 bpm |
| Zone 5 (VO₂ Max) | 90–100% | Maximum effort | Anaerobic power, sprint capacity | 171–190 bpm |
The classic formula — 220 minus age — is a rough estimate with a standard deviation of ±10–12 bpm. More accurate formulas include Tanaka (208 − 0.7 × age) and Gulati for women (206 − 0.88 × age). For the most precise zones, use the Karvonen method, which factors in resting heart rate to calculate Heart Rate Reserve (HRR), accounting for individual fitness. The Karvonen formula: Target HR = ((Max HR − Resting HR) × % Intensity) + Resting HR.2
Zone 2 training — the intensity where you can still hold a conversation — has gained significant attention from longevity researchers and elite coaches. Training at 60–70% of max HR builds mitochondrial density, improves fat oxidation, and develops the aerobic base that supports all other training. Elite endurance athletes spend 80% of their training time in Zone 2 (the "80/20 rule" of polarized training). For health and longevity, 150–180 minutes per week of Zone 2 exercise delivers the most cardiovascular benefit per time invested. Use our VO₂ Max Calculator to estimate your aerobic fitness level.3
Fat loss: Zone 2 burns the highest percentage of calories from fat, but higher zones burn more total calories per minute. A mix of Zone 2 (3–4 sessions) and Zone 4 intervals (1–2 sessions) per week optimizes both fat burning and metabolic rate. 5K/10K racing: Build base with Zone 2, develop speed with Zone 4 threshold work. Marathon: Primarily Zone 2 with tempo runs in Zone 3. General health: The AHA recommends 150 minutes of moderate activity (Zone 2–3) or 75 minutes of vigorous activity (Zone 4–5) per week.4
Heart rate training zones divide your cardiac effort into distinct intensity bands, each producing different physiological adaptations. Training in the right zone for your goals — whether fat burning, endurance building, speed development, or cardiovascular health — maximizes the efficiency of every workout minute.
Zone 1 (50–60% max HR) — Recovery: Very light effort, easy conversation possible. Used for warm-ups, cool-downs, and active recovery between hard sessions. Promotes blood flow to muscles without adding training stress. Most daily movement falls here. Zone 2 (60–70% max HR) — Aerobic Base: This is the foundation of endurance fitness. Comfortable pace where you can speak in full sentences. Builds mitochondrial density, capillary networks, and fat-burning efficiency. Elite endurance athletes spend 80% of their training time in Zone 2. A common mistake among recreational athletes is spending too little time here and too much in the unproductive "gray zone" (Zone 3). Zone 3 (70–80% max HR) — Tempo: Moderate effort, speaking becomes choppy. Improves lactate clearance and aerobic capacity but creates significant fatigue without the specific adaptations of higher zones. Often called "no man's land" because it is too hard for optimal aerobic development and too easy for peak performance gains. Use sparingly and purposefully.
Zone 4 (80–90% max HR) — Threshold: Hard effort, only short phrases possible. Trains your body's ability to sustain high-intensity work by raising lactate threshold — the point where lactate accumulates faster than your body can clear it. Intervals of 4–20 minutes at this intensity are the primary tool for improving race pace across distances from 5K to half marathon. Zone 5 (90–100% max HR) — VO2 Max: Maximum sustainable effort for 2–6 minutes. Develops peak aerobic power and maximum capacity. Extremely demanding and requires 48–72 hours recovery. Intervals of 2–5 minutes with equal rest periods are the standard protocol. Most people should limit Zone 5 work to 1–2 sessions per week.
The classic formula 220 minus age provides a rough estimate but carries a standard deviation of 10–12 BPM — meaning a 40-year-old's true max could be anywhere from 168 to 192 versus the predicted 180. More accurate alternatives include Tanaka's formula (208 − 0.7 × age), which better predicts across age ranges, and the HUNT formula (211 − 0.64 × age), validated in a large Norwegian population study. The only truly accurate method is a graded exercise test — incrementally increasing intensity on a treadmill or bike until exhaustion under medical supervision. Field tests (running a hard 3-minute all-out effort after a thorough warm-up) provide a practical approximation of max HR within 3–5 BPM for most healthy individuals.
The Karvonen method uses heart rate reserve (HRR) — the difference between your maximum and resting heart rate — to set more personalized zones. The formula is: Target HR = Resting HR + (HRR × intensity %). This method is more accurate than simple percentage-of-max because it accounts for fitness level through resting heart rate. A well-trained athlete with a resting HR of 48 and a sedentary individual with a resting HR of 78 will have very different zone boundaries even if their max HR is identical. Lower resting heart rate generally indicates better cardiovascular fitness and produces wider training zones.
Caffeine elevates resting and exercise HR by 5–10 BPM. Dehydration increases HR as the heart compensates for reduced blood volume — a 2% body weight fluid loss can raise HR by 7–10 BPM at the same exercise intensity. Heat and humidity increase cardiac demand through thermoregulation. Altitude raises HR due to reduced oxygen availability. Sleep deprivation elevates resting HR and reduces heart rate variability (HRV). Overtraining initially elevates resting HR but can paradoxically suppress it in advanced overtraining syndrome. Medications — beta blockers dramatically reduce max HR by 20–30%, making standard zone calculations unusable; consult your physician for adjusted guidelines.
Modern fitness trackers provide continuous heart rate monitoring, but data without context creates confusion. Focus on three key metrics: resting heart rate trend (declining over weeks indicates improving fitness), time in zone distribution (ensure 80% of training is in Zones 1–2 with 20% in Zones 4–5 for optimal endurance development), and cardiac drift (heart rate increasing during steady-effort exercise suggests dehydration, overheating, or inadequate aerobic fitness). Ignore single-session fluctuations — heart rate varies naturally by 5–10 BPM day to day based on sleep, stress, hydration, and nutrition.
Optical wrist sensors (found in most smartwatches) perform well during steady-state exercise but struggle with interval training, where rapid heart rate changes cause lag of 10–30 seconds compared to chest straps. Wrist sensors also lose accuracy during exercises involving significant wrist flexion (burpees, kettlebell swings, rowing) due to sensor displacement. For serious training — particularly threshold and VO2 max intervals where precise zone targeting matters — a chest strap monitor (Polar H10, Garmin HRM-Pro, Wahoo TICKR) provides medical-grade accuracy within 1–2 BPM. For general fitness tracking and Zone 2 sessions, wrist sensors are sufficient.
→ Use a chest strap for accuracy. Wrist-based optical sensors are ±5–10 bpm. Chest straps are ±1–2 bpm. The difference matters for zone training.
→ Don't ignore Zone 2. It feels "too easy" but builds the aerobic foundation. Most recreational athletes train too hard too often — more Zone 2 typically improves performance.
→ Measure resting HR in the morning. Take your pulse before getting out of bed for 3 consecutive days and average the results. Lower resting HR generally indicates better cardiovascular fitness.
→ Adjust zones after fitness changes. As fitness improves, your resting HR drops and your zones shift. Recalculate every 3–6 months.
See also: VO₂ Max Calculator · Running Pace · Calorie Burn · TDEE Calculator