Heart Rate Zone Calculator

Calculate your personalized heart rate training zones to optimize your workouts. This calculator uses the Karvonen method (Heart Rate Reserve) when you provide your resting heart rate, or simple percentage-based zones when you don't. Choose from three validated formulas for estimating maximum heart rate: Tanaka (recommended), Fox, or Gulati (for women).

What Are Heart Rate Training Zones?

Heart rate training zones are specific ranges of heartbeats per minute that correspond to different exercise intensities. Training in different zones produces different physiological adaptations, allowing you to target specific fitness goals like fat burning, endurance building, or speed development.

The Five Training Zones

Zone 1: Recovery (50–60%)

Zone 1 is the lightest intensity zone, used primarily for warm-ups, cool-downs, and active recovery between harder training sessions. At this intensity, you can easily hold a full conversation or even sing. This zone promotes blood flow and recovery without adding training stress.

Zone 2: Fat Burn (60–70%)

Zone 2 is often called the "fat-burning zone" or "aerobic base zone." This is where most of your training should occur if you're building endurance. At this intensity, your body primarily uses fat as fuel, and you develop mitochondrial density and aerobic efficiency. You can maintain conversation with some effort.

Understanding the "Fat-Burning Zone"

The term "fat-burning zone" is somewhat misleading and requires clarification. Zone 2 earns this label because at lower intensities, a higher proportion of your energy comes from fat (roughly 60–70%) compared to carbohydrates. As exercise intensity increases, your body shifts toward using a greater percentage of carbohydrates because they can be converted to energy more quickly.

However, this does not mean Zone 2 is the best zone for losing body fat. Higher-intensity exercise burns significantly more total calories per minute. Even though a smaller percentage comes from fat, the absolute amount of fat burned may be equal or greater. For example:

In this example, Zone 2 burns slightly more fat calories during the workout. However, high-intensity exercise also creates an "afterburn effect" (excess post-exercise oxygen consumption, or EPOC), where your metabolism remains elevated for hours after the workout, burning additional calories.

The bottom line for fat loss: Your total calorie deficit over time matters far more than which zone you train in. The best training zone for fat loss is whichever one allows you to exercise consistently, recover adequately, and maintain a sustainable routine. For most people, a mix of predominantly Zone 2 training with some higher-intensity sessions provides the best balance of fat burning, fitness improvement, and injury prevention.

Zone 3: Cardio (70–80%)

Zone 3, sometimes called "tempo" or "threshold" zone, represents moderate-to-hard effort. You can speak in short sentences but would struggle to hold a full conversation. This zone improves lactate clearance and cardiovascular efficiency, making it useful for race-pace training.

Zone 4: Threshold (80–90%)

Zone 4 training occurs at or near your lactate threshold, the point where lactate begins accumulating faster than your body can clear it. This is hard, sustainable effort used for interval training and race preparation. Speaking is difficult at this intensity.

Zone 5: Peak (90–100%)

Zone 5 represents maximal or near-maximal effort that can only be sustained for short periods (30 seconds to a few minutes). This zone develops anaerobic capacity, VO2max, and neuromuscular power. Speaking is not possible.

Methods for Calculating Zones

Percentage of Maximum Heart Rate (Simple Method)

The simplest approach multiplies your maximum heart rate by the zone percentages directly. While easy to calculate, this method doesn't account for individual fitness levels.

Karvonen Method (Heart Rate Reserve)

The Karvonen method, developed by Finnish physiologist Martti Karvonen in 1957, uses your heart rate reserve (HRR)—the difference between your maximum and resting heart rates. This method produces more personalized zones that correlate better with %VO2max and account for your current fitness level.

Notice how the Karvonen method produces a higher target heart rate (138 bpm vs 117 bpm) for the same zone percentage. This is because fitter individuals with lower resting heart rates have a larger heart rate reserve and can achieve higher training intensities within the same zone.

Maximum Heart Rate Formulas

If you haven't measured your maximum heart rate directly through a graded exercise test, you can estimate it using age-based formulas. This calculator implements three validated formulas:

Tanaka Formula (Recommended)

Developed from a 2001 meta-analysis of 351 studies involving 18,712 subjects, the Tanaka formula is more accurate than the traditional Fox formula, especially for older adults. The traditional 220-age formula tends to underestimate max HR in older individuals, which would result in training zones that are too low.

Fox Formula (Traditional)

The most widely known formula, appearing in Fox, Naughton, and Haskell's 1971 review. Despite its popularity, this formula was never rigorously validated and has a large standard error (±10–12 bpm). It tends to overestimate max HR in young adults and underestimate it in older adults.

Gulati Formula (Women-Specific)

Developed from a study of 5,437 asymptomatic women, the Gulati formula was designed to address the tendency of general formulas to overestimate max HR in women. Consider using this formula if you are female and the standard formulas seem to produce zones that feel too high.

Important Limitations

All age-predicted maximum heart rate formulas have significant individual variation, typically ±10–12 bpm. Some individuals may have actual max heart rates 15–20 bpm higher or lower than any formula predicts. Factors affecting max HR include genetics, training status, medication use, and altitude.

If accurate training zones are important for your goals (such as competitive athletics), consider measuring your actual maximum heart rate through a supervised graded exercise test or a field test protocol.

How to Measure Resting Heart Rate

For the most accurate resting heart rate measurement:

1. Measure upon waking: Take your pulse first thing in the morning, before getting out of bed, eating, or drinking anything. This is when your body is truly at rest.

2. Count for 60 seconds: For manual measurement, count your pulse for a full 60 seconds rather than multiplying a shorter count. This improves accuracy.

3. Measure for several days: Your resting heart rate can vary day to day based on sleep quality, stress, hydration, and other factors. Take measurements for 3–5 consecutive days and average the results.

4. Use a heart rate monitor: For convenience and accuracy, you can use a chest strap heart rate monitor or a wrist-based device (though wrist devices may be less accurate for some individuals).

Typical Resting Heart Rate Ranges

Average adults typically have resting heart rates of 60–80 bpm. Well-trained endurance athletes often have rates of 40–60 bpm, and elite athletes may have rates below 40 bpm. A decreasing resting heart rate over time is generally an indicator of improving cardiovascular fitness.

Important Medical Considerations

High-intensity exercise (Zones 4–5) places significant stress on your cardiovascular system. While this stress is beneficial for healthy individuals and leads to fitness adaptations, it can pose risks for certain people. You should seek medical clearance before engaging in vigorous exercise if you:

Have cardiovascular conditions: Including heart disease, high blood pressure, arrhythmias, or a history of heart attack or stroke. Exercise can be highly beneficial for many cardiac patients, but intensity levels should be determined in consultation with a cardiologist.

Have diabetes: Exercise affects blood sugar levels, and high-intensity training requires careful monitoring and potentially adjusting medication or food intake.

Are over 40 and have been sedentary: If you haven't exercised regularly and are starting a new program, begin gradually in Zones 1–2 and progress slowly over weeks or months.

Experience warning symptoms: Stop exercising immediately and seek medical attention if you experience chest pain or pressure, severe shortness of breath, dizziness or lightheadedness, irregular heartbeat or palpitations, or unusual fatigue.

Are pregnant: Exercise during pregnancy can be beneficial, but intensity recommendations differ. Consult with your healthcare provider about appropriate heart rate targets.

Take medications affecting heart rate: Beta-blockers and some other medications lower your maximum heart rate, making standard formulas inaccurate. Your doctor can help determine appropriate training zones.

Using Your Zones in Training

The 80/20 Principle

Research on elite endurance athletes consistently shows that most of their training time (approximately 80%) is spent at low intensities (Zones 1–2), with only about 20% at high intensities (Zones 4–5). This "polarized" approach builds aerobic capacity while allowing adequate recovery.

Zone-Specific Workouts

Easy runs and active recovery (Zone 1–2): The foundation of endurance training. Should feel comfortable and conversational.

Tempo runs (Zone 3): "Comfortably hard" effort, typically 20–40 minutes at a steady pace.

Threshold intervals (Zone 4): Intervals of 8–20 minutes at threshold pace with recovery periods.

VO2max intervals (Zone 5): Short, hard intervals of 2–5 minutes with equal or longer recovery.

Sprint intervals (Zone 5): Maximum effort bursts of 30 seconds to 2 minutes for power development.

References:

1. Tanaka H, Monahan KD, Seals DG. Age-predicted maximal heart rate revisited. J Am Coll Cardiol. 2001;37(1):153-156. https://pubmed.ncbi.nlm.nih.gov/11153730/
2. Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate; a longitudinal study. Ann Med Exp Biol Fenn. 1957;35(3):307-315.
3. Fox SM, Naughton JP, Haskell WL. Physical activity and the prevention of coronary heart disease. Ann Clin Res. 1971;3(6):404-432.
4. Gulati M, Shaw LJ, Thisted RA, Black HR, Bairey Merz CN, Arnsdorf MF. Heart rate response to exercise stress testing in asymptomatic women: the St. James Women Take Heart Project. Circulation. 2010;122(2):130-137. https://pubmed.ncbi.nlm.nih.gov/20585008/
5. Shookster D, Lindsey B, Cortes N, Martin JR. Accuracy of Commonly Used Age-Predicted Maximal Heart Rate Equations. Int J Exerc Sci. 2020;13(7):1242-1250. https://pmc.ncbi.nlm.nih.gov/articles/PMC7523886/
6. Robergs RA, Landwehr R. The surprising history of the "HRmax=220-age" equation. J Exerc Physiol Online. 2002;5(2):1-10.
7. American College of Sports Medicine. ACSM's Guidelines for Exercise Testing and Prescription. 11th ed. Wolters Kluwer; 2022.
8. Seiler S. What is best practice for training intensity and duration distribution in endurance athletes? Int J Sports Physiol Perform. 2010;5(3):276-291. https://pubmed.ncbi.nlm.nih.gov/20861519/