What is the Karvonen formula?

The Karvonen formula calculates target heart rate zones using your Heart Rate Reserve (HRR = Max HR − Resting HR). It is more accurate than basic percentage methods because it accounts for individual fitness level via resting heart rate.

How do I measure my resting heart rate?

Measure your resting heart rate first thing in the morning before getting up. Count your pulse for 60 seconds or count for 15 seconds and multiply by 4. Take the average over 3 consecutive mornings for best accuracy.

What is a good resting heart rate?

For adults, a normal resting heart rate is 60–100 bpm. Athletes often have resting heart rates of 40–60 bpm due to higher cardiovascular efficiency. Below 60 bpm is called bradycardia and may be normal or require medical evaluation.

What is Zone 2 training?

Zone 2 (60–70% of heart rate reserve) is moderate aerobic exercise where you can hold a conversation. It primarily burns fat for fuel, builds aerobic base, and improves mitochondrial density. Most endurance coaches recommend spending 70–80% of total training time in Zone 2.

VO2 max is the maximum volume of oxygen your body can use per minute per kilogram of body weight (mL/kg/min). It is the gold standard measure of cardiovascular fitness. Average values are 35–45 mL/kg/min for men and 27–38 for women. Elite endurance athletes exceed 70.

Is this heart rate zone calculator free?

Yes — completely free, no sign-up required. Results export to CSV or print as PDF.

Medical › Cardiology

Heart Rate Zone Calculator

Calculate your 5 personalised heart rate training zones using the Karvonen formula. Includes maximum heart rate, heart rate reserve, VO2 max estimate, and training guidance for each zone.

💓 Calculate Heart Rate Zones

Age (years)

Biological Sex (for VO2 max)

Resting Heart Rate (bpm — measure on waking)

Known Max Heart Rate (bpm, optional — overrides age formula)

Fitness Level (for VO2 max classification)

Advertisement — 468×60

—

Estimated VO2 Max

—

Training Zones — click any zone for details

Advertisement — 970×90

You May Also Need

❤️

Blood Pressure Tracker

Track and classify blood pressure alongside heart rate data.

🔥

Calorie Calculator

Match your daily calorie target to your training intensity.

⚖️

BMI Calculator

Track body composition alongside cardiovascular fitness.

⚡

BMR Calculator

Understand energy expenditure at rest vs during training.

Advertisement — 970×90

Heart Rate Training Zones Explained

Training in the right heart rate zone is one of the most effective ways to optimise cardiovascular fitness, burn fat, build endurance, and improve athletic performance. Different zones produce different physiological adaptations — understanding them helps you train smarter, not just harder.

The Karvonen Formula

The Karvonen (Heart Rate Reserve) formula is the gold standard for calculating personalised training zones because it accounts for your resting heart rate, making it far more accurate than simple age-based percentages:

Max HR: 220 − age (or use your known max HR)
Heart Rate Reserve (HRR): Max HR − Resting HR
Target HR: (HRR × intensity%) + Resting HR

The 5 Training Zones

Zone 1 (50–60% HRR): Active recovery, warm-up, fat burning at very low intensity
Zone 2 (60–70% HRR): Aerobic base building, fat oxidation, endurance foundation
Zone 3 (70–80% HRR): Aerobic conditioning, improves cardiovascular efficiency
Zone 4 (80–90% HRR): Lactate threshold training, high-intensity cardio, race pace
Zone 5 (90–100% HRR): Maximum effort, VO2 max development, sprints

VO2 Max Estimation

VO2 max is the maximum rate at which your body can consume oxygen during intense exercise — the gold standard measure of cardiovascular fitness. This calculator estimates it from age, sex, and fitness level using the Jackson-Blair-Mahar non-exercise estimation model. For clinical VO2 max testing, a graded exercise test (GXT) under supervision is required.

For a complete cardiovascular health picture, pair this tool with our blood pressure tracker and BMI calculator. For fitness-specific training plans, explore our Fitness & Wellness tools. To match nutrition to training intensity, use our calorie calculator.

⚠️ Consult your doctor before starting a new exercise programme, especially if you have a history of cardiovascular disease, hypertension, or are over 40.