The RPE scale is a tool that helps you measure how hard you’re exerting yourself during exercise.

Understanding how to use RPE is helpful for weightlifters because it gives you a simple, reliable, and scientific way to know when it’s safe to push for progress or cool your jets.

What’s more, it enables you to gain muscle and strength as quickly as possible while reducing your risk of injury, overreaching, and plateauing. 

In this article, you’ll learn everything you need to know about the RPE scale, including what the RPE scale is, why people use the RPE scale, and how you can use the RPE scale to build muscle faster.

What Is RPE?

RPE stands for “rating of perceived exertion” and is a subjective measurement of how hard you feel you’re training.

The measurement is based on the physical sensations you experience while you exercise such as how hard and deeply you’re breathing, your heart rate, how hot you feel, and how tired your muscles are.

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What Is the RPE Scale?

An RPE scale is a numerical scale that’s used to convert your subjective feelings about how hard you’re working into an objective number.

High numbers on the RPE scale represent exercising at or close to maximum effort, and low numbers represent exercising at a low intensity (like walking). 

The two most commonly used RPE scales are the Borg RPE scale and the Modified RPE scale. Let’s look at each separately.

The Borg RPE Scale

The Borg RPE scale, also known as the “Borg RPE scale 6-20” is named after Gunnar Borg, a Swedish researcher who introduced the concept of the RPE scale in several studies published in the 1950’s.

The 15-point Borg RPE scale ranges from 6-to-20, with 6 representing no exertion or rest, and 20 denoting maximum exertion or complete exhaustion. 

Here’s how it looks:

The Borg RPE Scale

The Borg RPE scale goes from 6-to-20 because if you multiply those numbers by 10, you’ll get a rough estimate of what your heart rate will be at each level of intensity, which is a reliable indicator of cardiovascular exertion.

For example, if your run feels like a 10 RPE your heart rate is probably in the ballpark of 100 beats per minute.

That brings us to one of the drawbacks of the original Borg RPE scale: it’s designed for cardio workouts, not strength workouts, where heart rate isn’t closely correlated with physical effort.

There are three other downsides to the original chart:

  1. It can be difficult to determine exactly where you fall on the scale without practice because it offers so many options (“am I at 15, 16, or 17?”).
  2. Studies show that heart rates can vary quite a bit person-to-person at the same workout intensity. That is, two people of a similar size who are running at the same pace might have very different heart rates. 

All that is why Borg eventually developed a more universally practical RPE scale known as the Modified RPE scale.

Modified RPE Scale

The Modified RPE scale, also known as the “CR10 RPE scale” or the “RPE scale 1-10,” is a 10-point scale that can be used to measure many kinds of perceptions, sensations, and subjective experiences, including perceived exertion, pain, and dyspnea (breathlessness).

There are many different version of the Modified RPE scale floating around the internet, but they all look more or less like this:

The Modified RPE Scale


The Modified RPE scale RPE scale is simpler to use and easier to understand than its predecessor, and it isn’t based on heart rate, which makes it more useful for strength athletes.

For example, a 0 on the Modified RPE scale would be something akin to moving your arms in a bench press motion, which takes basically no effort, and a 10 would be grinding out a new one-rep max on your bench press.

Why Do People Use RPE?

The main reason people use RPE scales is to control their workout intensity, which is a critical component to getting fitter over time. 

Using RPE helps you strategically add or subtract weight and reps based on how you’re feeling on a day-to-day basis, while also ensuring that your muscle and strength gains trend upward over time.

If you’ve spent any time lifting heavy weights, you know that individual workouts can feel significantly easier or harder depending on a number of factors, including how much sleep you’re getting, what your diet looks like, how much you’re training, and how much life stress you’re dealing with.

For most of us, most of these things remain fairly stable, which is why many workout programs have you add weight on a regular schedule based on a percentage of your one-rep max or an arbitrary amount like 5 or 10 pounds each week.

There’s one problem with this approach, though: actual progress is never perfectly linear.

Due to the factors noted above and others, some days you’d be able to add more weight than the plan calls for, and other days you may not be able to add any at all, or may even have to reduce the weight on the bar.

For example, if all of your sets feel like a “7” on a scale of 1-to-10, but your training plan says you should only add 5 pounds, why should you hold back when you could probably add 10 or 15 pounds?

On the other hand, if all of your sets feel like a “9” or “10” on a scale of 1-to-10, should you trust the program and keep adding weight, knowing that you’re already on the stretch?

RPE helps you effectively navigate these situations, because it gives you an objective framework to determine what you should do to ensure safe, long-term progress.

By adjusting your training based on RPE, you get the maximum muscle-building stimulus out of every workout, without pushing so hard that you increase the risk of getting injured.

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A Better Way to Think About RPE for Weightlifters

While the Modified RPE scale is more applicable to weightlifting than the Borg RPE scale, neither is ideal

This is because people have trouble connecting their subjective ratings with objective levels of exertion when they’re lifting weights.

For example, in some studies people will rate a set as a 9 RPE but stop several reps shy of failure based on one-rep max calculations, while in other studies, people will give RPE scores of between 6 and 9 out of 10, even when they take sets to absolute failure.

Fortunately, several studies show there’s a more accurate way to think about RPE for weightlifters: an RPE scale based on “Reps in Reserve.”

To understand how it works, try this:

At the end of a hard set, just before re-racking your weights, ask yourself, “If I absolutely had to, how many more reps could I have gotten with good form?”

Your answer is known as your “Reps In Reserve (RIR),” or how many reps you could’ve done, but didn’t, and if you’re like most people, this is how you naturally talk about your weightlifting sets.

For instance, after a set of hard squats, you might say, “Man, that was a grinder—I had maybe 1 rep left in the tank.” 

Not only do RPE and RIR track the same variable (intensity), they’re highly interchangeable, which means that they correlate nicely with each other, too.

Here’s how the RPE scale that’s based on RIR looks:

PRE scale based on reps in reserve


Thus, a 10 RPE is a 0 RIR, a 9 RPE is a 1 RIR, and so forth, meaning that when you say a set was a 7 RPE, you’re saying that you had 3 reps left in the tank, and vice versa.

That said, RPE has its drawbacks:

  1. Learning to use RIR takes some time. When you’re new to weightlifting (especially heavy weightlifting), it may be hard to accurately estimate your reps in reserve. The more you practice, though, the better you’ll get (I’ve found most people get the hang of it after two to three weeks).
  2. The further you are from failure on each set, the less accurate RIR becomes. RIR is most effective when you’re using heavy weights (80%+ of your one-rep max, or the 6-to-8 rep range and lower), and taking each set to the point of 1-to-3 reps shy of failure.
  3. RIR requires that you be honest about your ratings. If you tell yourself that a set felt easier than it really was so that you can move up in weight faster, you’ll sabotage your progress in the long run. This kind of introspection can feel irksome, but it’s necessary to progress consistently over time.  

How to Use RPE to Build Muscle Faster

There are many ways to use RPE in your training, but most are overly complex.

To get the majority of the benefits that RPE-based training has to offer, here’s what I use and recommend, what’s proven to work in the research, and what’s worked well for the thousands of people who’ve read my books and followed my programs for men and women:

1. Decide the rep range you want to use.

You can use RPE-based training for any rep range, of course, but I generally recommend working with weights in the range of 75-to-85% of your one-rep max, or in the range of 6-to-8 (~80%) to 4-to-6 (~85%) reps.

2. Decide on your RPE range and convert it to RIR.

Studies show an RPE of 7-to-9 (an RIR of 3-to-1 reps) is a sweet spot of sorts for maintaining the proper intensity in your workouts without going to failure too often, which can limit your progress and increase your risk of injury.

3. Determine your starting weights.

Follow these steps to determine your starting weights:

1. Determine your current rep maxes for the exercises you’ll be doing using the Legion One-Rep Max Calculator.

2. On the calculator, find the “Estimated reps” column, and then find the number in that column that’s 2 reps higher than the top of your target rep range.

For example, if your target rep range is 4-to-6 reps, trace down the “Estimated reps” column until you reach 8.

Or, if your target rep range is 6-to-8 reps, trace down the “Estimated reps” column until you reach 10.

This will ensure you’re using a weight that has you ending your sets at an RIR of 1 to 3 rather than 0, which ensures more consistent progress over time.

3. The number in the “Weight” column immediately to the left of your finger is your starting weight. 

For example, if your bench press one-rep max is 225 pounds and you want to train in the 4-to-6-rep range, you’d enter 225 in the Legion One-Rep Max Calculator. Then, you’d find the number 8 in the “Estimated reps” column. Then, look at the number in the “Weight” column next to the number 8, and that’s what you’ll want to train with (it’s 180 pounds).

Tip: Round your starting weights to the nearest 5. If the calculator says you should use 138 pounds, go with 140. If it says you should use 92 pounds, use 90, and so on. 

4. Increase the weights as fast as you can while still staying within your rep range and RPE limits.

The best way to do this is using double progression, which works like this:

Let’s say your workout calls for 4-to-6 reps of overhead press. If you get 6 reps on your first set with 1-to-3 reps in the tank, add 5 pounds to each side of the bar (10 pounds total) for your next set and work with that weight until you can (eventually) press it for 6 reps with at least 1 RIR, and so forth.

If you get 3 or fewer reps with your new (higher) weight on your next sets, reduce the weight by 5 pounds to ensure you can stay within your target rep range and RPE limits (4-to-6 reps and 1-to-3 RIR) for all sets. (For more pointers on how to use double progression to gain muscle and strength, check out this article).

FAQ #1: What does RPE stand for?

RPE stands for “rating of perceived exertion.” 

FAQ #2: What does RPE mean?

RPE is a subjective measurement of how hard you feel you’re training.

If your program calls for a set of bench press at RPE 8 (and you’re using the RPE scale based on RIR discussed above), it means you should finish your set when you feel like you have 2 reps left in the tank. 

FAQ #3: What is an RPE calculator?

An RPE calculator  is similar to a one-rep max calculator insofar as you use it to calculate your estimated one-rep max.

The difference is a one-rep max calculator uses just weight lifted and number of reps completed to arrive at an estimated one-rep max, whereas an RPE calculator uses weight lifted, number of reps, and RPE to calculate estimated one-rep max. 

The problem with RPE calculators is their accuracy relies on how honestly you report RPE. For instance, if you say a heavy set of squats felt like an RPE 8 when it was actually an RPE 9.5, you’ll get an inflated sense of what your squat one-rep max actually is.

For this reason I recommend you stick to using a one-rep max calculator to track your estimated one-rep max over time. 

FAQ #4: What is an RPE chart?

An RPE chart is a chart devised by powerlifting coach and “RPE guru,” Mike Tuchscherer, that roughly correlates an RPE and rep range to a percentage of one-rep max.

Every RPE chart is unique because it’s based on your own personal data, but here’s an example of what one looks like:

RPE Chart

RPE charts can be useful if you follow a powerlifting program that relies on RPE to regulate your training. If you don’t use the RPE scale for powerlifting programming, however, you don’t need to use an RPE chart.

FAQ #5: How do you calculate RPE?

The best way to calculate the RPE of a set is to ask yourself just before you re-rack the weight at the end of a hard set, “If I absolutely had to, how many more reps could I have gotten with good form?”

Your answer is known as your “Reps In Reserve (RIR),” or how many reps you could have done.

For instance, if after a set of hard squats you think you could have done one more rep, your RIR would be 1.

Both RIR and RPE are rated out of 10, and they’re inversely related, so . . .

  • If your RIR is 1, your RPE is 9
  • If your RIR is 2, your RPE is 8
  • If your RIR is 3, your RPE is 7

 . . . and so forth.

Thus, if you know your RIR you can quickly calculate your RPE.

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FAQ #6: Who developed the RPE scale?

Swedish professor Gunnar Borg first introduced the concept of perceived exertion in the 1950s. He then went on to develop the Borg RPE scale and the Modified RPE scale (or CR10 scale) over the following few decades.

In the recent past, powerlifting coach Mike Tuchscherer developed the idea of RPE based on RIR, which is the most accurate version of RPE for weightlifters. 

FAQ #7: What is RPE in running?

RPE in running is basically the same as RPE in weightlifting—it’s a measure of how much you’re exerting yourself. 

One difference, however, is when you use the Borg RPE scale in running you can estimate your heart rate by multiplying your rating of perceived exertion by 10. 

For instance, you might rank an easy run as a 9 or a 10 on the Borg RPE scale which would mean your estimated heart rate for that run would be around 90-to-100 beats per minute.

+ Scientific References