Find your 5 training heart rate zones. Uses both Karvonen (heart rate reserve) and percentage of max HR methods.
Heart rate training zones give you a precise, objective way to control exercise intensity. Without zone guidance, most people train too hard on easy days (leaving them fatigued for hard days) and not hard enough on hard days (failing to create the stimulus needed for adaptation). This "grey zone" mistake is the most common training error for recreational athletes and is the primary reason many people plateau in fitness despite consistent training. Our heart rate zones calculator uses both the simple percentage-of-max-HR method and the more accurate Karvonen heart rate reserve method to give you personalised training zones for every workout.
Zone 1 (50-60% max HR) is very light recovery activity — walking, easy cycling, gentle swimming. Primary fuel source is fat. Used for active recovery between hard sessions and for warming up. Zone 2 (60-70% max HR) is the aerobic base zone — conversational pace where you can hold a full sentence but feel your breathing elevated. The most important zone for endurance development, fat adaptation and aerobic mitochondrial density. Should comprise 70-80% of all training volume. Zone 3 (70-80% max HR) is moderate aerobic tempo work — you can speak in short sentences but are clearly working. Trains aerobic power and lactate threshold. Zone 4 (80-90% max HR) is the threshold zone — uncomfortable, can only speak single words. Trains lactate threshold, the pace you can sustain for approximately 30-60 minutes. Zone 5 (90-100% max HR) is maximum effort — cannot speak, only used in short intervals or racing. Trains VO2 max and anaerobic capacity. Use our VO2 max calculator to estimate your aerobic ceiling and our running pace calculator to convert heart rate zones into equivalent running paces.
| Zone | % Max HR | Feel | Primary Fuel | Training Benefit | Typical Use |
|---|---|---|---|---|---|
| Zone 1 | 50-60% | Very easy | Fat (90%) | Recovery, base | Warm-up, cooldown |
| Zone 2 | 60-70% | Easy, conversational | Fat (70-85%) | Aerobic base, fat adapt | Long runs, base training |
| Zone 3 | 70-80% | Moderate, short sentences | Mixed (50/50) | Aerobic power | Tempo work, cruise intervals |
| Zone 4 | 80-90% | Hard, single words | Carbs (70-80%) | Lactate threshold | Threshold intervals, race pace |
| Zone 5 | 90-100% | Maximum, no talking | Carbs (100%) | VO2 max, speed | HIIT, short intervals, racing |
The simple percentage-of-max-HR method treats all people with the same max HR as having identical aerobic capacity, which is not true. A fit person with a resting HR of 45 bpm and a sedentary person with a resting HR of 80 bpm, both with a max HR of 185 bpm, have very different heart rate reserve (HRR = max HR minus resting HR): 140 vs 105 bpm. The Karvonen formula personalises zones using HRR: Target HR = ((Max HR - Resting HR) x intensity%) + Resting HR. For Zone 2 at 60-70% HRR, the fit person targets 129-143 bpm while the sedentary person targets 123-133 bpm — meaningfully different zones at the same percentage. The Karvonen method is particularly important for people with either very low (athletic) or very high (deconditioned) resting heart rates, where simple max HR percentages give misleading zone boundaries.
The 220 minus age formula is widely used but has poor individual accuracy — it can be off by 10-20+ bpm for a given individual. The Tanaka formula (208 - 0.7 x age) used in our calculator is more accurate across age ranges, with a standard deviation of approximately 7 bpm. The most accurate way to find your max HR is a maximal effort field test: after a proper warm-up, run 4 minutes very hard up a hill (8-10% grade), recover 3 minutes, then run 4 minutes at absolute maximum effort. The highest HR recorded during or immediately after is close to your true max HR. Alternatively, a 5K race effort often brings most people to within 95-98% of their true max HR. GPS sports watches with optical heart rate sensors can capture this during competition. Use the measured value in our calculator above for the most accurate zone boundaries.
| Age | Est. Max HR (Tanaka) | Zone 2 (60-70%) | Zone 4 (80-90%) | Zone 5 (90-100%) |
|---|---|---|---|---|
| 20 | 194 | 116-136 | 155-175 | 175-194 |
| 30 | 187 | 112-131 | 150-168 | 168-187 |
| 40 | 180 | 108-126 | 144-162 | 162-180 |
| 50 | 173 | 104-121 | 138-156 | 156-173 |
| 60 | 166 | 100-116 | 133-149 | 149-166 |
| 70 | 159 | 95-111 | 127-143 | 143-159 |
Zone 2 training has received significant attention in endurance sports research and among performance coaches in recent years. At Zone 2 intensity (60-70% max HR), the primary metabolic pathway is aerobic fat oxidation — mitochondria in slow-twitch muscle fibres burn fat with oxygen. Consistent Zone 2 training increases mitochondrial density and size, improves fat oxidation capacity, improves lactate clearance (enabling higher Zone 4-5 efforts), and builds the capillary network that delivers oxygen to muscles. The so-called 80/20 rule — 80% of training in Zone 1-2, 20% in Zone 4-5 — is supported by research on both elite athletes and recreational runners. The most common mistake recreational athletes make is spending too much time in Zone 3 (too hard to be genuinely easy, too easy to provide a real hard-session stimulus) and not enough time in genuine Zone 2. Use our calories burned calculator to estimate calorie expenditure across different zones and our BMI calculator to track body composition changes as aerobic fitness improves.
Training zone distribution should reflect your primary fitness goal. For fat loss and body composition: prioritise Zone 2 for the majority of cardio sessions (3-4 per week) with 1-2 higher-intensity sessions (Zone 4-5). Zone 2 maximises fat oxidation per session and accumulates high training volume without excessive recovery demand. For cardiovascular health and longevity: 150 minutes per week in Zone 2 meets major health guidelines, with additional Zone 4-5 work optional but beneficial. For endurance performance (5K to marathon): follow the 80/20 model — 3-4 Zone 2 sessions per week plus 1-2 threshold or interval sessions. For maximum VO2 max improvement: increase Zone 4-5 proportion to 20-25% while maintaining Zone 2 base. The Norwegian 4x4 HIIT protocol (4 x 4 minutes at Zone 5 with 3-minute Zone 1-2 recovery) is highly effective and should be limited to 1-2 sessions per week. Use our TDEE calculator to adjust caloric intake as training volume increases and our VO2 max calculator to track aerobic fitness improvements over time.
Accurate heart rate data requires a reliable monitor. There are two main technologies: chest strap monitors and wrist-based optical monitors. Chest straps (Polar H10, Garmin HRM-Pro, Wahoo TICKR) measure the electrical signal of the heartbeat (ECG-based) and are accurate to within 1-2 bpm even during intense exercise, rapid heart rate changes, and interval training. They are the gold standard for training zone accuracy, particularly for high-intensity work where wrist monitors lag. Wrist-based optical monitors (Apple Watch, Garmin GPS watches, Fitbit) use photoplethysmography (PPG) -- shining green light into the wrist and measuring blood volume changes. They are highly accurate at steady-state intensities (Zone 1-3) but can lag by 15-30 seconds during rapid heart rate increases (starting a hard interval) and can be affected by wrist movement, skin tone, wrist hair and tight or loose fit. For Zone 2 base training where heart rate is stable, wrist monitors are adequate. For Zone 4-5 interval training, a chest strap gives more accurate real-time feedback. Many Garmin and Polar GPS watches support both optical wrist HR and an external chest strap -- a practical combination for mixed training. Our VO2 max calculator provides the aerobic fitness context that makes heart rate zone training most useful, and our calories burned calculator uses heart rate data to refine calorie estimates across different exercise intensities.
Overtraining occurs when training load consistently exceeds recovery capacity, and chronic Zone 3 training is a common contributor. Signs of overtraining include elevated resting heart rate (more than 5-7 bpm above normal), poor sleep quality, persistent fatigue, declining performance despite consistent training, and reduced motivation. Monitoring resting heart rate daily (measuring immediately upon waking before getting out of bed) is one of the simplest early warning indicators of accumulated fatigue. An elevation of 5+ bpm above your normal baseline suggests inadequate recovery and a need for easier training. Heart rate variability (HRV) -- the variation in time between heartbeats -- is a more sensitive recovery indicator used by elite athletes and increasingly available through consumer fitness devices. Higher HRV generally indicates good recovery and readiness for hard training. Training your zones correctly, with genuinely easy Zone 2 sessions on easy days, reduces overtraining risk and produces more consistent long-term performance improvements. Our VO2 max calculator tracks aerobic fitness progress and our TDEE calculator helps match caloric intake to increasing training loads to support recovery.