One of the best ways to gauge your workout intensity is to monitor your heart rate.
Because your heart rate is correlated with the intensity level of any type of physical activity, and the association is fairly linear, your heart rate during exercise can be an effective and practical way to quantify your effort level and estimate the number of calories you burn.
For this reason, heart rate training for runners has long been one of the most scientific approaches to endurance training and is fairly easy to carry out once you have a heart rate monitor and have defined your heart rate zones.
However, determining your heart rate zones can be as simple or complicated as you’d like it to be; the difference lies in how accurate you want your heart rate zones to be.
The more precise you are about how to calculate max heart rate, the more accurate your heart rate training will be.
But you need to know how to calculate max heart rate. Are maximum heart rate estimations adequate, or should you actually measure maximum heart rate with a test?
In this article, we will discuss how to calculate max heart rate and why it might be worth measuring your maximum heart rate rather than relying on an estimated maximum heart rate equation.
We will cover:
- What Is Maximum Heart Rate?
- Factors That Affect Max HR
- How to Calculate Max Heart Rate
- Measuring Maximum Heart Rate
- Do I Need to Measure Maximum Heart Rate?
Let’s get started!
What Is Maximum Heart Rate?
Your maximum heart rate (MHR or max HR) refers to your highest potential pulse, or the maximum number of times your heart can beat in a minute, measured in beats per minute.
The faster your heart is capable of beating, the higher your maximum heart rate.
Factors That Affect MHR
Interestingly, all of the widely-used formulas on how to calculate max heart rate only take into consideration your age and sometimes your sex.
While your age and sex are the two factors that most significantly impact your maximum heart rate, there are other additional factors as well.
The primary factors that affect your maximum heart rate include:
- Age: Your maximum heart rate decreases with age.
- Genetics: Your genes can influence your MHR.
- Body size: Although not true across the board, people with a smaller body size tend to have a higher maximum heart rate because the heart muscle is smaller.
- Sex: Again, although not true in all cases, women tend to have a lower maximum heart rate than men, according to the American College of Cardiology.
- Altitude: Being at altitude can depress your maximum heart rate.
- Fitness level: While your fitness level and training experience don’t seem to have much bearing on your max heart rate; if you are doing a field test or laboratory test to actually measure your max heart rate rather than estimate it with an equation, if you aren’t fit or accustomed to the type of exercise you’re doing, it might be difficult to achieve a true maximum.
For example, If you are doing a graded treadmill run and you have never run, fatigue in your legs or mental/physical discomfort might force you to voluntarily stop early before you reach your true max.
How to Calculate Max Heart Rate
There are quite a few formulas for calculating your maximum heart rate, as researchers have continually tried to fine-tune the accuracy of MHR equations based on further testing and more data.
Some of the most common formulas for how to calculate max heart rate are as follows:
The most common formula used for calculating max heart rate is also the simplest: 220 minus age in years.
For example, if you’re 36 years old: 220-36 = 184 bpm.
This formula can be used for both men and women and is typically the MHR formula used by fitness watches and exercise machines that calculate your heart rate zones based on your age.
However, while this way of calculating maximum heart rate is simple, it’s not particularly accurate.
Despite its popularity of use, research indicates that the standard deviation of the maximum heart rate equation of 220 – age in years is +/- 12 beats per minute.
The Gulati formula for max heart rate was developed specifically for women after researchers consistently noted that the Fox Formula generally overestimates MHR for women.
This formula for calculating max HR is for women only: 206 – (0.88 × age).
The HUNT Fitness Study measured the maximum heart rate in 3,320 healthy adults aged between 19 and 89. The data was then used for a regression analysis to find the line of best fit.
The formula that describes the trend line for maximum heart rate based on age is 211 – (0.64 x age).
The HUNT formula for max HR is said to be better for active men and women, and the researchers found it to be more accurate than 220 – age or other common formulas for calculating maximum heart rate.
That said, the error margin is still about 10.8 beats per minute.
The Tanaka formula for calculating max heart rate is primarily designed for men and women over age 40 because the traditional 220-age formula tends to have higher errors for older adults.
This formula is 208 – (0.7 × age).
Other Max HR Formulas:
According to researchers, a more accurate estimation than the Fox Formula for max heart rate can be found through the following formulas:
- Maximum Heart Rate for Males = 208.609-0.716 x age
- Maximum Heart Rate for Females = 209.273-0.804 x age
For example, if you’re a 36-year old male: 208.609-0.716 x 36 = 183 bpm. If you’re a 36-year old female: 209.273-0.804 x 36 = 180
Another study came to the max HR equation of 209.3 – 0.72 x age, but this formula still had an error of +/- 11.8 bpm.
Measuring Your Maximal Heart Rate
The gold standard for measuring your maximum heart rate is to do a graded maximum exercise test in a laboratory setting.
However, another way of how to calculate max heart rate is by doing a field test on your own.
This will also involve pushing yourself to your maximum capacity, which takes a lot of motivation and hard work, but it is essentially free and probably much more accurate than relying on one of the MHR equations.
Because a max heart rate field test requires true maximum exertion, it is advisable to speak with your healthcare provider before doing the test if you are over the age of 40 and/or have any underlying medical conditions.
Once you have medical clearance and feel confident in your physical health, you just need a heart rate monitor.
Theoretically, you can measure your max heart rate using any type of cardio exercise, such as running, cycling, rowing, or climbing stairs, but running is usually the easiest way for most people to actually find their true maximum heart rate.
With the other forms of exercise, particularly cycling and rowing, localized muscle fatigue (tired legs or arms) can force you to stop early rather than getting to your true cardiovascular maximum.
Here is a field test to measure your maximum heart rate:
- Warm up by running 1-3 miles, depending on your fitness level.
- Run one mile on a track at tempo pace, but with 400 meters to go, ramp up to an all-out effort.
- Sprint the last 100 meters as fast as possible.
- Review your heart rate data from the last 400 meters; the highest number recorded is your maximum heart rate.
Another good field test for measuring your maximum heart rate is as follows:
- Warm up by jogging for 10-15 minutes.
- Run one mile at tempo pace or a pace that you could hold for 10k or 45-60 minutes of running.
- Without stopping when your mile is over, increase your pace by 2 seconds per 200 meters every single 200 meters until you cannot run faster. Note that if you are running on a 400-meter track, this means you will want to run each half lap 2 seconds faster than the previous half lap until you can no longer increase your running pace.
- The peak heart rate that gets displayed on your heart rate monitor before you have to slow down is your maximum heart rate.
Let’s give a practical example here. If you can run 10k in 50 minutes, your pace is 8 minutes per mile or 5 minutes per kilometer.
So your first tempo mile (four laps of the track) should be run in 8 minutes, with each lap taking 2 minutes.
Then, when you begin the ramp-up portion of the test, your first 200 meters (half lap) should be run in 58 seconds, and the second 200 should be in 56 seconds for a total lap time of 1:54.
Without stopping, you move into your next 200 meters, which should be run in 54 seconds, and the second half of the track should be covered in 52 seconds, and so on.
As soon as you can’t run faster, you can slow down and stop.
If you don’t have access to a track, but you do have a GPS running watch, you can replicate this same protocol by increasing your pace by 20 seconds per mile every minute you run after the tempo mile.
For example, the same runner would start at an 8 min/mile pace and then increase their speed to 7:40 min/mile for the first minute, 7:20 min/mile the second minute, 7:00 min/mile the third minute, and so on until you cannot run faster.
For runners more comfortable dealing with distances in kilometers, you can increase your pace by 15 seconds per kilometer every minute.
Do I Need to Measure Maximum Heart Rate?
Depending on your fitness goals, it might be totally fine to calculate your max HR from a formula, but it’s important to keep in mind that there are clearly large margins of error with these calculations.
Most of the formulas for calculating max heart rate have a standard deviation of at least 10 to 12 bpm.
Therefore, your heart rate training zones can all be shifted up or down depending on where your true maximum heart rate falls relative to age-matched peers.
If you want to be as scientific as you can about your training, it’s worth the time and effort to measure your maximum heart rate with a field or laboratory test.
Learning how to calculate max heart rate is most valuable for runners or other athletes who notice a discrepancy between your heart rate during exercise and your perceived exertion or effort level because this is a good sign that you’re probably one of the outliers for whom the max HR equations don’t accurately estimate your maximum heart rate.
For example, if you are a runner in decent shape trying to stay within the aerobic zone for your workouts—defined to be 70-80% of your maximum heart rate—but find that your heart rate is way faster than it “should” be based on how your heart rate zones are defined, you might have a maximum heart rate that is 10-12 beats per minute faster than the mean value described by the formula you used to calculate max HR.
By measuring your actual maximum heart rate, you can shift your heart rate zones up to where they should be, giving you a better workout and a more accurate way to guide your training and effort.
Now that you know how to calculate max heart rate, let’s figure out your heart rate training zones.