Heart Rate Zone Calculator

What Are Heart Rate Training Zones?

Heart rate zones divide your heart rate range into 5 intensity levels. Training in different zones produces different adaptations: recovery, endurance, aerobic fitness, anaerobic capacity, and maximum effort.

The Karvonen Method

Unlike simple percentage-of-max formulas, the Karvonen method uses your heart rate reserve (max HR − resting HR). Target HR = ((MaxHR − RestHR) × intensity%) + RestHR. This personalizes zones based on your fitness level.

The Fat Burning Zone Myth

Zone 2 (60–70%) burns a higher percentage of fat per calorie, but total fat loss depends on total calories burned. Higher intensity burns more total calories. For weight loss, focus on total energy expenditure and consistency.

How to Find Your Resting Heart Rate

Measure your pulse first thing in the morning before getting out of bed. Count beats for 60 seconds (or 15 seconds × 4). Average over several days. A lower resting HR generally indicates better cardiovascular fitness.

Which Max HR Formula to Use

Tanaka (208 − 0.7 × age) is the most accurate for most adults. Fox (220 − age) is simpler but tends to overestimate. Gulati (206 − 0.88 × age) is better for women. Lab testing is the gold standard.

Zone 2 Training for Fat Loss and Endurance

Zone 2 (60–70% of max HR) is where your body burns the highest percentage of fat as fuel. While higher-intensity zones burn more total calories per minute, Zone 2 is sustainable for longer sessions and builds your aerobic base. Most endurance coaches recommend spending 80% of training time in Zone 2. It improves mitochondrial density, capillary growth, and fat oxidation — adaptations that benefit both performance and body composition over time.

How to Train in Each Zone

Zone 1 (Recovery): Easy walking, light stretching — used for warm-up and cool-down. Zone 2 (Fat Burn): Brisk walking, easy jogging, cycling — conversational pace. Zone 3 (Aerobic): Tempo runs, moderate cycling — can speak in short sentences. Zone 4 (Anaerobic): Interval training, hill sprints — can only say a few words. Zone 5 (VO2 Max): All-out sprints, max effort intervals — unsustainable beyond 1–3 minutes.

Heart Rate Monitors: Chest Strap vs. Wrist

Chest strap monitors (like Polar H10) measure electrical signals from your heart and are the most accurate for real-time zone training. Optical wrist sensors (found in smartwatches) are convenient but can lag during high-intensity intervals and may be inaccurate during activities with wrist movement. For serious zone-based training, a chest strap provides the most reliable data. Wrist monitors are adequate for steady-state cardio and general tracking.

Nutrition for Zone-Based Training

Different training zones have different fuel demands. Zone 1–2 sessions primarily burn fat and don't require special fueling for sessions under 90 minutes. Zone 3–4 sessions rely more on glycogen — ensure adequate carbohydrate intake before and after. Zone 5 sessions are short but intense; a small carb-rich snack 30–60 minutes before can help performance. Post-workout protein (20–40g) supports recovery regardless of the zone you trained in.