Workout Intensity Calculator

Rating of Perceived Exertion (RPE)

Rating of Perceived Exertion (RPE) is a subjective measure of the intensity of your activity.

The amount of energy converted depends on your ability to consume oxygen and the intensity of the activity.

Intensity can be divided into non-pace and pace activities. Intensities of all physical activities can be determined by using Rating of Perceived Exertion (RPE). Intensities of activities like running, walking, swimming, or cycling can also be determined by distance.

In the 1960s Dr. Gunnar Borg developed RPE. He knew that lab equipment could determine intensity, but he wanted to see if people could accurately estimate intensity for themselves. During an exercise test he had them attached to measuring devices, but also asked them to select keywords from a chart to describe their feelings. He found that the relationship between what the machines measured and what the subjects described had a .93 correlation (1.0 being a perfect 1-1 correlation).

This meant that most people could accurately assess the intensity of their physical activity.

Adjusting for Cardiovascular Drift

Cardiovascular drift refers to the natural increase in heart rate with little or no change in running pace. Research has shown that it is common to see cardiac “drift” upward during an easy or threshold run by as much as 10-20bpm over a 30mins period. One way to adjust for cardiac drift is to learn to use the RPE table to intuitively assess your intensity. You won’t be perfect with this method at first, so wear the heart rate monitor and use it the first 10-15 minutes of your run to get you on track. Then, cover it up and practice running by feel. Look at the data only after you’re done running and compare your breathing rhythm and the effort you felt to the heart rate numbers.

NOTE: The KEY to success of this system is in your ability to rate your intensity honestly

Rating of Perceived Exertion (RPE) Table

RPE Running Intensity HR Zone %HRR Race Pace Estimator Breathing Intensity Ability To Talk During The Run
1 Very Easy 1 50 – 70 Recovery Run / Jog Easy Effortless
2 Easy Easy Run Ultramarathon Normal Easy
3 Moderate 2 71 – 80 Comfortable Comfortable
4 Somewhat strong Aerobic Run Noticeable Somewhat difficult
5 Strong 3 81 – 87 Deep but steady breathing Difficult
6 Between strong and very strong Marathon Deep & somewhat laboured Between difficult and very difficult
7 Strong to very strong 4 88 – 93 Half / 15k / 10mi Deep & laboured Very difficult (short sentences)
8 Very strong 10k Very deep & very hard Extremely difficult (short phrases)
9 Very, very strong 5 95 – 100+ 3k / 5k Breathlessness Impossible to talk
10 Maximum effort 1500m / 1mi / 3k Breathlessness Impossible to talk

* If you are new to running, you can use your Heart Rate Monitor (HRM) to help you gauge your efforts for accurately. Over time, an experienced runner should be able to find the right exercise intensity by feel! The indicated Heart Rate Zones (HRZ) is a rough estimate (varies a bit from individual to individual due to different body physiology) to keep your from going outside your prescribed workout intensity.

Calculating Heart Rate Zones (HRZ)

The first step to finding your HR zones is figuring out your maximum heart rate (mHR). You can find maximum heart rate several ways.

The most accurate is to have a graded exercise test to exhaustion (commonly referred to as a V02 max test) in a lab. But this can be costly. The second most accurate way is to perform a field test. This involves some type of maximal workout to exhaustion while measuring HR every so often. When maxed out, whatever number your heart rate monitor displays is probably somewhere close to your max. This one is easy to try. Start by running a mile or two warm-up, then one mile (or 1500m) at tempo pace. Begin increasing speed with 500m to go, and go all out in the last final 400m. Record your HR afterwards. Athletes of all types can do this one, shortening the distance if necessary.

A less taxing way? Most calculators use a validated prediction equation to calculate estimated max heart rate. One frequently used is:

mHR Estimator
(mHR = 218 – 0.8 x [age])

The second step is to determine your resting heart rate (rHR).

Watch Brand LINK Instruction

Click Here

Use the Heart Rate Widget on your watch
Apple watchApple

Click Here

Use the Heart Rate app

Click Here

Under section Daily HR

Click Here

Under section What’s Resting Heart Rate

Applying the Karvonen formula to calculate HR zones based on desired intensity.

The Karvonen formula uses a number known as heart rate reserve (HRR) to calculate your exercise heart rate at given intensity (%).

HRR is the difference between max and resting heart rate. HRR = mHR – rHR


ExerciseHR = targetIntensityPct * (mHR – rHR) + rHR

Workout Intensity Calculator

Heart Rate Zones Calculator

Enter your HR Information:
% mHR HRZONE HR (bpm) Min HR (bpm) Max
50 – 70 1
71 – 80 2
81 – 87 3
88 – 93 4
95 – 100+ 5