Forget the guesswork — fitness just got easier to master. As fitness trackers grow in popularity alongside workouts that use the devices like Orangetheory Fitness and Peloton’s Power Zone program, you now have easy access to biometrics, like heart rate zones, that can guide smarter workouts and give you an edge to hit your goals.

Heart rate zones are a tool that help you gauge how hard your body is working during exercise by breaking down your maximum heart rate into specific intensity levels, explains Dr. Steven Stache Jr., chief of Rothman Orthopaedic Institute‘s non-operative sports medicine division, Philadelphia Phillies team physician and chief medical officer at Drexel University Athletics. Think of these zones as ranges that show how fast your heart beats per minute, with each range corresponding to a different effort level — from light activity, like a leisurely walk, to all-out sprints at maximum effort.

These zones are more than just numbers — they’re a road map to more intelligent training. “Each zone can be used to optimize exercise with a purpose, such as burning fat, improving endurance or boosting speed. In essence, using heart rate zones is like applying ‘speed limits’ for your heart during exercise,” he continues. You can train precisely and see better results by tailoring your intensity to your goals.

Here’s what to know about heart rate zones, how to use them to train effectively and how to get started, with or without a tracking device.

What are heart rate zones?

Heart rate zones measure how hard your heart works during exercise by dividing your effort into intensity levels. The five levels are calculated as percentages of your maximum heart rate, which is the highest number of beats per minute your heart can safely manage.

According to personal trainer Tara De Leon, each zone offers distinct health and performance benefits. Here’s an overview:

• Zone 1 (55-65% of max heart rate): This is the “conversational pace” zone. You work at a light intensity, so you can easily chat without losing your breath. This pace is ideal for burning fat and is sustainable for long periods, making it great for improving overall health and engaging in active recovery between more challenging workouts.

• Zone 2 (65-75% of max heart rate): Here, you’re still in fat-burning territory but at a slightly higher intensity. You can hold a conversation, but you might need to take a breather occasionally. “In Zone 2, you’re enhancing aerobic endurance, building a strong cardiovascular base and improving fat metabolism,” De Leon explains.

• Zone 3 (75-85% of max heart rate): At this moderate to high intensity, your body burns a mix of fat, carbohydrates and protein for fuel. Talking requires effort, as your breathing is heavier. “Working in Zone 3 increases aerobic capacity, improves overall fitness and enhances the body’s ability to transport and use oxygen,” De Leon says.

• Zone 4 (85-95% of max heart rate): This is where the intensity ramps up. You’re working hard and can only sustain it for up to about 15 minutes (depending on where you fall in the 85-95% range). At this level, your body shifts to burning carbohydrates and protein. Training in Zone 4 enhances speed, endurance and anaerobic capacity — your ability to perform intense bursts of effort.

• Zone 5 (95-100% of max heart rate): The max effort zone. You’re going all out, burning carbohydrates and protein, with no energy for talking. This level of intensity can only be maintained for up to a few minutes at a time (sometimes only a few seconds, depending on exactly how intensely you’re working) and is designed to boost anaerobic capacity and develop explosive power.

How to calculate your heart rate zones

Using the Karvonen formula is the most common way to calculate heart rate zones. At a glance, this formula looks complicated:

([maximum heart rate – resting heart] x % intensity) + resting heart rate = training zone

However, it’s easier than you might think when broken into steps. Here’s how it works:

Find your maximum heart rate (MHR)

The simplest way to estimate your MHR is by subtracting your age from 220. For example, if you’re 45, your estimated MHR would be 175 (220 – 45 = 175).

For a slightly more accurate estimate, you can use the Tanaka Method, calculated as 208 – (0.7 x age). Using the same example, a 45-year-old’s MHR would be 176.5 (208 – (0.7 x 45) = 176.5). This method is often used by fitness programs like Orangetheory Fitness, according to their vice president of fitness, Scott Brown.

Determine your resting heart rate (RHR)

Your RHR is how often your heart beats per minute when you’re completely at rest. For most adults, this falls between 60 to 100 BPM (endurance athletes may have a lower RHR). You can measure it using a fitness tracker or by counting the pulse at your wrist while sitting still.

Calculate your heart rate reserve (HRR)

HRR is the difference between your maximum and resting heart rates. For example, if your MHR is 175 and your RHR is 65, your HRR would be 110 (175 – 65 = 110).

Find your target heart rate zones

Use your HRR to finalize your Karvonen formula calculations and find your target heart rate for each zone. Simply multiply your HRR by the percentage of maximum effort each zone represents, then add your RHR. You can use these zone percentages to make the calculations:

• Zone 1: 50% (or 0.5) of HRR + RHR

• Zone 2: 60% (or 0.6) of HRR + RHR

• Zone 3: 70% (or 0.7) of HRR + RHR

• Zone 4: 80% (or 0.8) of HRR + RHR

• Zone 5: 90% (or 0.9) of HRR + RHR

Using the example HRR of 110 calculated above, your Zone 2 target would be (110 x 0.6) + RHR (65) = 131 BPM.

Alternative methods

You can informally observe perceived exertion if you want to skip the math. If you can easily hold a conversation, you’re likely in Zones 1 or 2, but if talking is more challenging, you’re likely in Zones 3 or 4. And if you’re working so hard you can’t talk at all? You’re certainly in Zone 5.

While these methods provide helpful estimates, the most precise way to determine your heart rate zones is through a VO2 max test conducted by a cardiologist or exercise physiologist. These tests are often performed in hospitals, sports performance labs or universities.

Using heart rate zones in your workouts

Understanding your heart rate zones can eliminate the guesswork associated with exercise. It allows you to measure your effort and train intentionally to achieve your goals.

“Instead of guessing how hard you should push yourself, you monitor your heart rate and adjust your effort to stay within a specific range. This approach can help you meet your fitness goals, whether that’s building stamina, burning calories or improving overall performance,” says Stache. “Heart rate zone training ensures you’re exercising at the right intensity for your goals, so you don’t waste time doing too much or too little.”

Using a fitness tracker, you can monitor your real-time heart rate during workouts to identify your zone and make sure you’re reaping the benefits tailored to your goals:

• Zone 1: Promotes blood flow and low-stress aerobic conditioning and is perfect for warm-ups, cool-downs and active recovery.

• Zone 2: Builds endurance and maximizes fat burning.

• Zone 3: Improves overall aerobic fitness and enhances oxygen efficiency.

• Zone 4: Boosts cardiovascular efficiency, speed and performance.

• Zone 5: Enhances peak performance, power and overall cardio capacity.

While Zone 1 is best for warming up and cooling down, how much time you spend in other zones depends on your fitness goals and level:

• Training for a marathon? Spend more time in zones 2 and 3 to build endurance.

• Looking to boost speed and power? Incorporate intervals in zones 4 and 5.

• Aiming for weight loss? Focus on zones 1-3 to maximize fat burning, although adding interval training in the more challenging zones can also help build muscle and increase post-exercise calorie burn.

Brown highlights the importance of training across all five zones: “Your body uses two key energy sources. By training in all zones, you help your body adapt to using both efficiently, ensuring metabolic flexibility.”

Ease the guesswork and invest in a fitness tracker

Fitness trackers are invaluable for monitoring your heart rate and tracking the time spent in various heart-rate zones. We tested 18 popular models to find the best options, and you can learn about our findings here. If you’re looking to start heart-rate training, here are a few of our favorite models.

Factors affecting heart rate

Heart rate is a valuable metric, but it’s not the only information you should hang your hat on. “Heart rate isn’t a perfect measurement. It can be influenced by environmental factors like humidity and temperature, stimulants, pharmaceuticals, sleep and stress,” says Brown.

Additional factors such as age, fitness level and hydration also play a role in how your heart rate responds during activity. “With all that said, it’s still one of the easiest and most accessible biometrics to tap into. It offers insight into your body that moves beyond just perception,” Brown adds.

If you want to use heart rate training to maximize your workouts, it’s important to also pay attention to how your body feels and how intensely you feel you’re working. Hard data paired with personal perception can help guide your workouts and ensure you’re getting the most out of every minute spent sweating.

FAQs

What is the best heart rate zone for weight loss?

Training in zones 1 through 3 burn fat at a higher percentage than carbohydrates, so individuals with weight loss goals may want to spend most of their training time here. De Leon also encourages interval training.

“You burn a large percentage of fat in Zone 2, but you’re not burning a huge amount of calories overall. If you bump it up to zones 3 or 4, you won’t burn as big of a percentage of fat, but because of the increased calorie burn, you’ll burn more fat overall. This is one of the reasons interval training is so popular.”

How accurate are heart rate monitors?

Fitness trackers aren’t medical-grade devices, so their readings may not always be 100% accurate. However, research consistently shows that chest strap monitors provide the most reliable and precise data compared to other trackers.

What should I do if I can’t reach my target heart rate zone?

If your heart rate is below your target zone, try increasing the intensity of your workout by picking up the pace or adding hills and intervals. If it’s too high, slow down, remove intervals or take extra rest breaks.

If you’re consistently unable to stay within your target zone, consider consulting your physician or other healthcare professional to rule out any underlying medical concerns affecting your heart rate.

Is it safe to train in the maximum heart rate zone?

If you’ve been medically cleared for high-intensity exercise, training in Zone 5 is generally safe — but only for short bursts of up to a few minutes at a time. Also, listen to your body and stop if you experience pain or discomfort. You may also want to work with a trainer or coach if you’re new to more intense exercise sessions to ensure you’re not pushing yourself too hard based on your current fitness level.

How often should I check my heart rate during a workout?

Monitoring your heart rate during a workout is a great way to gauge how your body responds. However, if constant checking feels distracting or affects your form, pay attention to your body’s natural cues instead. These can serve as an effective feedback loop to keep your intensity in check without compromising your workout.

Meet our experts

• Tara De Leon, MS, CSCS and master personal trainer at Edgewater Fitness

• Dr. Steven Stache Jr., chief of the non-operative sports medicine division at Rothman Orthopaedic Institute, team physician for the Philadelphia Phillies and chief medicine officer at Drexel University Athletics

Our health content is for informational purposes only and is not intended as professional medical advice. Consult a medical professional on questions about your health.