How to calculate your heart rate during exercise: 2 formulas to calculate your target heart rate

Have you spent 30–40 minutes jogging, cycling, or doing cardio but still haven't seen the results you expected? One common reason is not training at the correct intensity. Many people train too lightly, burning fewer calories, while others train too hard, causing their bodies to tire quickly and making it difficult to sustain long-term.

According to international health and sports organizations, maintaining your target heart rate during exercise can help improve cardiovascular training effectiveness, enhance endurance, and support better weight management. However, not everyone knows how to calculate their heart rate, determine their target heart rate, or understand which heart rate zone is appropriate for their age and physical condition.

In this article, Tiptory will guide you on how to calculate your target heart rate simply, easily, and quite accurately. With just a few basic calculations or a heart rate monitor, you can determine the appropriate training intensity to optimize the effectiveness of each workout and protect your cardiovascular health long-term.

Part 1: How to Calculate Standard Heart Rate Using the Karvonen Formula

Step 1: How to Calculate Maximum Heart Rate

Determine Maximum Heart Rate (HRmax)

Maximum heart rate is the highest number of times your heart can beat per minute during maximum exertion. This is an important basis for calculating your target heart rate, establishing your training heart rate zone, and controlling appropriate exercise intensity.

To estimate your maximum heart rate by age, you can use the formula:

• Maximum Heart Rate (HRmax) = 207 - (0.7 × age)

Example of maximum heart rate calculation

• If you are 39 years old:
• HRmax = 207 - (0.7 × 39)
• HRmax = 207 - 27.3
• Result ≈ 180 beats/minute (bpm)

This means your heart can reach approximately 180 beats/minute during maximum exertion.

Notes when using the HRmax calculation formula

• Maximum heart rate is only an estimated value, which can vary depending on gender, physical condition, training level, and health status.
• Most people do not need and should not try to reach their maximum heart rate during exercise.
• There is no need to use a heart rate monitor to determine HRmax at this step, as the formula already uses age to provide an initial reference value.

Should the "220 minus age" formula be used?

• The "220 - age" formula was once widely used to calculate maximum heart rate.
• However, many experts now believe that the formula 207 - (0.7 × age) provides more suitable results for various age groups.
• Nevertheless, the 220 - age formula can still be used for quick estimation when calculating your heart rate during exercise or your fat-burning zone.

Accurately determining your maximum heart rate, target heart rate, and training heart rate zone will help you exercise cardio more effectively, improve cardiovascular health, and reduce the risk of overtraining.

Step 2: How to Measure Resting Heart Rate

Check Resting Heart Rate (RHR)

Resting Heart Rate (RHR) is the number of times your heart beats per minute when your body is in a complete state of relaxation. This is an important indicator for calculating your target heart rate, assessing cardiovascular health, and accurately applying the Karvonen method.

To measure your resting heart rate, do it immediately after waking up in the morning, before getting out of bed.

• Place your index and middle fingers on the inside of your wrist or on either side of your neck, near your windpipe.
• Find the spot where you can clearly feel your pulse.
• Use a watch with a second hand or a timer function.
• Start counting from the first beat as zero.
• Count the total number of heartbeats in 30 seconds.
• Multiply the result by 2 to calculate the number of beats in 1 minute.

Example of resting heart rate calculation

• If you count 32 beats in 30 seconds:
• RHR = 32 × 2
• RHR = 64 beats/minute (bpm)

This is your resting heart rate.

Increase accuracy when measuring heart rate

Heart rate can change slightly day by day. For more reliable results, it's best to measure it on 3 different mornings and take the average value.

For example:

• Day 1: 62 bpm
• Day 2: 65 bpm
• Day 3: 63 bpm

Calculation method:

• (62 + 65 + 63) ÷ 3 = 63.3

Thus, your average resting heart rate is approximately 63 bpm.

Factors that can affect resting heart rate

Before measuring, try to limit factors that alter heart rate for more accurate results:

• Smoking or exposure to nicotine.
• Drinking coffee, strong tea, or other caffeinated beverages.
• Stress, anxiety, or lack of sleep.
• Excessively hot or cold weather.
• Hormonal changes in the body.
• Certain medications prescribed by a doctor.

Accurately measuring your resting heart rate is a crucial step in precisely calculating your training heart rate zone, optimizing cardio effectiveness, and monitoring long-term cardiovascular health.

Step 3: How to Calculate Heart Rate Reserve

Calculate Heart Rate Reserve (HRR)

Heart Rate Reserve (HRR) is the difference between your maximum heart rate and your resting heart rate. This index indicates how much capacity your heart has left to work when exercise intensity increases.

In the Karvonen method, HRR is a crucial basis for calculating your target heart rate during exercise, helping to determine the appropriate training intensity for each individual rather than relying solely on age.

Formula:

• HRR = HRmax - RHR

Where:

• HRmax is the maximum heart rate.
• RHR is the resting heart rate.

Example of calculating heart rate reserve

Assume:

• Maximum heart rate (HRmax): 180 beats/minute.
• Resting heart rate (RHR): 63 beats/minute.

Apply the formula:

• HRR = 180 - 63
• HRR = 117 beats/minute

Thus, your heart rate reserve is 117 bpm.

Why is the HRR index important?

• Helps accurately calculate the target heart rate for each training level.
• Reflects the cardiovascular system's ability to adapt to physical activity.
• Supports building more effective cardio, jogging, cycling, or weight loss plans.
• Personalizes training intensity based on each individual's actual physical condition.

A simple understanding of heart rate reserve

Imagine your resting heart rate as the starting point and your maximum heart rate as the highest limit your heart can reach. The difference between these two levels is the "operational budget" your heart can use when you walk briskly, jog, go to the gym, or perform high-intensity cardiovascular exercises.

After determining your HRR, you can proceed to calculate your target heart rate zone to know at what level your heart rate should be maintained to burn fat, build endurance, or improve cardiovascular health.

Step 4: How to Calculate Minimum Target Heart Rate

Calculate Minimum Target Heart Rate (Target HRMin)

After determining your heart rate reserve (HRR), you can calculate your minimum target heart rate to know the heart rate level you should aim for when exercising at a moderate intensity. This training zone is suitable for beginners, inactive individuals, or those returning to exercise after a long break.

To calculate the minimum target heart rate, take 50% of your heart rate reserve.

Formula:

• Heart rate increase = HRR × 0.5

Example of calculating heart rate increase

Assume:

• Heart rate reserve (HRR): 117 beats/minute

Apply the formula:

• 117 × 0.5 = 58.5 beats/minute

The result shows that your heart rate needs to increase by approximately 58.5 bpm compared to your resting rate to reach a moderate activity level.

Calculate minimum target heart rate

After obtaining the heart rate increase, add this value to your resting heart rate (RHR).

Formula:

• Minimum target heart rate = RHR + (HRR × 0.5)

Example:

• Resting heart rate (RHR): 63 bpm
• Heart rate increase: 58.5 bpm

Perform the calculation:

• 63 + 58.5 = 121.5 bpm

Thus, your minimum target heart rate is approximately 122 beats/minute.

When should you train in this heart rate zone?

• Beginners to exercise.
• Individuals building a daily exercise habit.
• Older adults needing to exercise at a safe intensity.
• Individuals recovering from injury or a long period of inactivity.
• Individuals wanting to improve cardiovascular health without putting too much strain on the body.

Benefits of maintaining a minimum target heart rate

• Helps the body gradually adapt to physical activity.
• Reduces the risk of overtraining.
• Improves blood circulation and cardiovascular function.
• Increases foundational endurance to prepare for higher training levels.
• Supports maintaining a long-term and sustainable exercise habit.

Accurately determining your minimum target heart rate is an important step in calculating your heart rate during exercise, helping you train safely and achieve better results according to the Karvonen method.

Step 5: How to Calculate Average Target Heart Rate

Calculate Average Target Heart Rate (Target HRMod)

As health and fitness improve, you can gradually increase your exercise intensity by raising the percentage of your heart rate reserve (HRR) utilized. Instead of using the 50% level for basic training, many people choose a range from 60% to 70% to achieve better results in building endurance and improving physical fitness.

Formula:

• Target Heart Rate = RHR + (HRR × intensity percentage)

Where:

• RHR is the resting heart rate.
• HRR is the heart rate reserve.
• Intensity percentage is usually between 0.6 and 0.7 for average training intensity.

Example of calculating target heart rate at 70%

Assume:

• Resting heart rate (RHR): 63 bpm
• Heart rate reserve (HRR): 117 bpm

Apply the formula:

• Target heart rate = 63 + (117 × 0.7)
• Target heart rate = 63 + 81.9
• Result ≈ 145 bpm

Thus, your average target heart rate will be approximately 145 beats/minute.

Common target heart rate levels

Based on the same example above:

• 60% intensity: 63 + (117 × 0.6) ≈ 133 bpm
• 65% intensity: 63 + (117 × 0.65) ≈ 139 bpm
• 70% intensity: 63 + (117 × 0.7) ≈ 145 bpm

This heart rate zone is commonly used for cardio workouts, brisk walking, light jogging, or cycling at moderate intensity.

Who should train in the average heart rate zone?

• Individuals who have been exercising regularly for some time.
• Individuals who want to improve cardiovascular endurance.
• Individuals aiming for fat loss and increased fitness.
• Individuals who want to increase the effectiveness of cardio compared to basic activity levels.

Notes when increasing training intensity

• If you are new to exercise, maintain a heart rate zone of 50%–60% initially.
• Gradually increase intensity according to your body's adaptation capacity, rather than increasing too quickly.
• Monitor for feelings of fatigue, shortness of breath, or dizziness to adjust appropriately.
• Frequent exercisers or athletes can choose levels of 70% or higher to achieve performance enhancement goals.

Maintaining an average target heart rate helps balance effectiveness and safety, and is an important transition step before moving to high-intensity training heart rate zones.

Step 6: How to Calculate High-Intensity Target Heart Rate

Calculate High-Intensity Target Heart Rate (Target HRIntense)

Once you have a good fitness foundation, you can train in the high-intensity heart rate zone to boost endurance, improve athletic performance, and increase your cardiovascular system's adaptability. According to the Karvonen method, this training level typically uses about 85% of your heart rate reserve (HRR).

Formula:

• High-intensity target heart rate = RHR + (HRR × 0.85)

Where:

• RHR is the resting heart rate.
• HRR is the heart rate reserve.

Example of calculating high-intensity target heart rate

Assume:

• Resting heart rate (RHR): 63 bpm
• Heart rate reserve (HRR): 117 bpm

Step 1: Calculate 85% of heart rate reserve

• 117 × 0.85 = 99.45 bpm

Step 2: Add to resting heart rate

• 63 + 99.45 = 162.45 bpm

Result:

• High-intensity target heart rate ≈ 162 bpm

Who is this heart rate zone suitable for?

• Individuals who have been exercising regularly for an extended period.
• Individuals with goals to improve athletic performance.
• Individuals who train with running, cycling, or high-intensity cardio exercises.
• Athletes or experienced exercisers.

Benefits of the high-intensity heart rate zone

• Increases endurance during exercise.
• Improves heart and lung function.
• Enhances stamina and training performance.
• Helps burn more energy in a short amount of time.
• Helps the body adapt better to strenuous workouts.

Notes when training at high intensity

• Do not maintain this heart rate zone for too long if you do not have an appropriate fitness foundation.
• Beginners or individuals with heart conditions should consult a doctor before applying this.
• If chest pain, unusual shortness of breath, dizziness, or a dangerously fast heart rate occurs, reduce intensity or stop exercising immediately.
• Warm up thoroughly and increase intensity gradually to allow your body to adapt safely.

After calculating your minimum target heart rate, average target heart rate, and high-intensity target heart rate, you can actively choose the training zone that suits your goals for weight loss, endurance improvement, or cardiovascular health.

Part 2: How to choose the appropriate heart rate zone for exercise

Step 1: How to check heart rate during exercise

Monitor heart rate during exercise

After calculating your target heart rate, the next step is to check if your actual heart rate falls within your desired training zone. Monitoring your heart rate during exercise helps adjust exercise intensity appropriately, avoiding exercising too lightly or too strenuously.

How to manually measure heart rate during exercise

• Pause your exercise for a few seconds.
• Immediately place your index and middle fingers on your wrist or either side of your neck to feel your pulse.
• Count the number of heartbeats in 10 seconds.
• Resume exercising after completing the measurement.
• Multiply the counted beats by 6 to calculate your heart rate per minute.

Formula:

• Heart rate (bpm) = Number of beats in 10 seconds × 6

Example of heart rate calculation during exercise

• If you count 24 beats in 10 seconds:
• Heart rate = 24 × 6
• Result = 144 beats/minute (bpm)

Then, compare this result with your previously calculated target heart rate zone to determine if your current exercise intensity is appropriate.

How to evaluate the results

• If your heart rate is below the target zone: You can increase your speed or exercise intensity.
• If your heart rate is within the target zone: Continue maintaining the current exercise level.
• If your heart rate exceeds the target zone for an extended period: You should reduce intensity to avoid overstraining your cardiovascular system.

Use heart rate monitors for more accurate tracking

Modern fitness trackers can continuously monitor your heart rate during exercise without requiring you to stop your workout.

• Smartwatches.
• Fitness trackers.
• Dedicated heart rate chest straps.
• Exercise equipment with integrated heart rate sensors.

These devices allow real-time monitoring of heart rate fluctuations, helping you easily maintain the correct training heart rate zone and optimize the effectiveness of cardio, running, or cycling workouts.

Notes for accurate heart rate measurement

• Measure immediately after stopping exercise, as heart rate can drop very quickly after just a few seconds of rest.
• Avoid talking or moving much while checking your pulse.
• Perform measurements multiple times during different workouts to get an overall view of your body's response.
• Combine monitoring actual sensations such as breathing, fatigue level, and ability to sustain exercise to comprehensively assess exercise intensity.

Regularly checking your heart rate during exercise helps you maintain the correct target heart rate, enhance workout effectiveness, and protect long-term cardiovascular health.

Step 2: How to adjust exercise intensity based on heart rate

Use target heart rate to assess exercise intensity

Once you've determined your target heart rate (THR), you can use this index to know if you're exercising at a light, moderate, or high intensity. This is a simple way to effectively control your workout and reduce the risk of overexertion.

Compare your actual heart rate during exercise with the previously calculated target heart rate zone.

Low to moderate intensity exercise

• Heart rate falls in the middle of the target heart rate zone.
• Typically equivalent to about 50%–70% of maximum heart rate (HRmax).
• You can still speak in short sentences while exercising but feel your breathing quicken more than usual.

This intensity level is suitable for:

• Beginners in exercise.
• Individuals looking to improve cardiovascular health.
• Individuals who are losing weight or maintaining weight.
• Extended workouts with moderate pressure.

High-intensity exercise

• Heart rate approaches the upper limit of the target heart rate zone.
• Typically equivalent to about 70%–85% of maximum heart rate.
• Breathing becomes rapid, and conversation becomes more difficult.

This intensity level is suitable for:

• Individuals with a good fitness base.
• Individuals looking to improve endurance and exercise performance.
• High-intensity cardio workouts or specialized sports training.

How should beginners start?

If you are just starting an exercise routine, you should:

• Start at a low to moderate heart rate zone.
• Maintain a stable intensity for the first few weeks.
• Gradually increase workout duration or intensity as your body adapts.
• Avoid trying to reach the high-intensity heart rate zone immediately.

Increasing intensity too quickly can lead to body fatigue, increased risk of injury, and difficulty maintaining a long-term exercise routine.

Maintain a low heart rate during warm-up and cool-down

During the warm-up and recovery phases after exercise, heart rate should be kept below the main target zone.

• Warm-up helps the body gradually adapt to exercise.
• Cool-down helps the heart rate gradually return to normal.
• Reduces feelings of dizziness or hypotension after finishing the workout.

Do not let heart rate exceed the maximum level

During exercise, it is important to monitor your heart rate regularly to avoid exceeding your maximum heart rate (HRmax).

If you experience any of the following symptoms, you should reduce intensity or stop exercising:

• Unusual shortness of breath.
• Dizziness or lightheadedness.
• Chest pain or tightness.
• Heart beating too fast or prolonged palpitations.

Maintaining your training heart rate within the appropriate zone will help optimize cardio effectiveness, improve cardiovascular health, enhance endurance, and reduce the risk of issues related to overexertion.

Step 3: Listen to your body's response during exercise

Monitor your body's actual response

Formulas for calculating target heart rate, maximum heart rate, or training heart rate zones are only estimates. Each person has a different physical condition, health, and adaptive capacity, so you should combine these calculations with monitoring your body's actual sensations during exercise.

If you notice that your body is not responding appropriately to the calculated heart rate zone, adjust your exercise intensity to ensure long-term safety and effectiveness.

Signs that you are exercising at a moderate intensity

When exercising in the low to moderate heart rate zone, the body typically exhibits the following signs:

• Starts to sweat lightly to moderately.
• Breathing is faster than usual but still controllable.
• Can hold short conversations during exercise.
• Feels like the body is working effectively but not overly fatigued.

If you are new to exercise, you might experience mild muscle soreness 1–2 days after your workout. This is a common reaction when muscles are unaccustomed to the exercise intensity.

Signs that you are exercising at a high intensity

As you approach the upper limit of your target heart rate zone, your body often reacts more noticeably:

• Breathing becomes rapid and deep.
• Difficulty maintaining a continuous conversation.
• Can only say a few words before needing to catch your breath.
• The perceived effort of exercise significantly increases.

This state is common in high-intensity cardio workouts, fast running, or advanced endurance training sessions.

Warning signs that require stopping exercise immediately

Stop exercising and seek medical attention if you experience unusual symptoms such as:

• Severe shortness of breath or uncontrollable breathing.
• Chest pain or sharp pain in the chest area.
• Severe muscle or joint pain.
• Dizziness, lightheadedness, or loss of balance.
• Excessive and unusual sweating.
• Exhaustion or severe fatigue even if the exercise intensity is not too high.

These could be signs that your body is under stress beyond its adaptive capacity or related to health issues that require professional evaluation.

Adjust target heart rate when necessary

If you frequently feel overwhelmed when reaching your calculated target heart rate, consider:

• Reducing the intensity of your workout.
• Lowering your target heart rate zone to match your current physical condition.
• Increasing the adaptation period before raising intensity.
• Consulting a doctor or physical therapist if you have underlying medical conditions.

The goal of monitoring your heart rate during exercise is not to achieve the highest number, but to maintain an appropriate level of activity to improve cardiovascular health, increase endurance, and reduce the risk of injury. An effective workout plan always starts with understanding and respecting the signals your body is sending you.

Notes when applying target heart rate

Maintain heart rate within the target zone during exercise

During physical activity, try to keep your heart rate during exercise within the calculated target heart rate zone (THR). This helps your body receive optimal benefits from cardiovascular exercises, while also supporting endurance improvement and enhancing overall health.

When heart rate is maintained within the appropriate zone:

• The cardiovascular system functions more efficiently.
• Oxygen absorption and utilization are improved.
• Energy burning effectiveness is optimized.
• The risk of overtraining is reduced.

Target heart rate is only a reference value

Although target heart rate calculation formulas are widely used, they are still only estimates based on age and individual metrics.

You should combine this with monitoring:

• Feelings of fatigue during exercise.
• Breathing and ability to speak.
• Recovery time after activity.
• Overall comfort level during the workout.

If you frequently feel exhausted or lose strength too quickly even when exercising within your target heart rate zone, it is likely that the current intensity is not suitable for your physical condition.

Adjust intensity when the body is overloaded

Some signs that you should reduce exercise intensity:

• Prolonged fatigue after exercise.
• Difficulty completing the planned workout.
• Abnormally fast heart rate for an extended period.
• Feeling out of breath even with moderate activity.
• Longer than usual recovery time.

In this case, reduce your speed, shorten your workout duration, or lower your target heart rate zone until your body adapts better.

Who should consult a doctor before exercising

Not everyone should calculate and apply their target heart rate without professional advice. You should consult a doctor before starting a new exercise program if you belong to one of the following groups:

• Have a history of cardiovascular disease.
• Are taking medications that affect heart rate or blood pressure.
• Have high blood pressure or other cardiovascular conditions.
• Are overweight or obese.
• Are over 40 years old and have been inactive for a long time.
• Have recently returned to exercise after many years of inactivity.

Build a safe and sustainable exercise plan

A doctor or medical professional can help you:

• Assess your current health status.
• Determine an appropriate training heart rate zone.
• Choose safe types of physical activity.
• Reduce the risk of cardiovascular events during exercise.

Understanding and correctly applying heart rate calculation methods, target heart rate, and training heart rate zones will help you exercise more effectively. However, the most important factor is still listening to your body and adjusting intensity to suit your actual capabilities.

References

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Content edited by: Rowan Hudson Le.

Information consulted and verified by expert: Andrew Collins.