If you want to know how to use the RPE scale to safely gain muscle and strength faster, then you want to read this article.

Key Takeaways

  1. RPE stands for rating of perceived exertion, which is a numerical measurement of how hard exercise feels.
  2. The best way for weightlifters to measure RPE is estimating “Reps In Reserve,” or how many more reps can be done before failure.
  3. You can often gain muscle and strength faster by adding and subtracting weight based on your Reps In Reserve, instead of regularly or arbitrarily adding or removing weight from the bar.

One of the most important aspects of weightlifting is progression.

This is the difference between exercise (moving your body to burn calories and improve health) and training (exercising according to a plan designed to produce specific long-term outcomes).

This is the key to avoiding stagnation in muscle and strength gain, and to breaking through the many plateaus that will occur throughout your fitness journey.

There are a number of ways to progress in your weightlifting workouts, but many of the most practical and effective ones share this in common:

They involve prescribed levels of difficulty in individual sets.

In other words, some sets are supposed to be moderately challenging, while others are supposed to involve near-maximum effort.

For example, one of my favorite progression models is known as double progression, and it works like this:

You work with a given weight in a given rep range, and once you hit the top of that rep range for one, two, or three sets (depending on the programming), you move up in weight, and work with it until you hit the top of your rep range again for the required number of sets, move up, and so on.

In this way, you first progress in your reps with a given weight, and then progress with the amount of weight you’re lifting. Hence, “double progression.”

Here’s a key question though:

How difficult are these sets supposed to be?

Well, if you want to get the most out of double progression, you want to end your working (heavy) sets one or two reps shy of failure.

In other words, you want your working sets to be pretty damn difficult.

This way of looking at the difficulty of exercise (in this case, weightlifting), brings us to the topic at hand: the RPE scale.

As you’ll soon see, the RPE scale is a simple but powerful tool for workout programming, and especially for strength training, because it can help you gain muscle and strength faster while simultaneously reducing the risk of injury or overtraining.

Let’s start by defining exactly what RPE is.

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What Is RPE?

RPE stands for rating of perceived exertion.

There are different ways to express RPE, but they all provide the same thing: a numerical measurement of how hard exercise feels.

This concept was developed by a Swedish researcher named Gunnar Borg, who introduced it in several studies published in the 1950’s.

Borg found that our subjective ratings of effort during exercise are often a reliable and in some cases a superior way to measure intensity than “hard numbers” like running speed, weight on the bar, bar speed or path, and so forth.

He created a table to help represent these subjective ratings called the Borg RPE Scale, which looks like this:

borge 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, it’s likely your heart rate is about 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 is no longer closely correlated with physical effort.

There are 3 other downsides to the original chart:

  1. The numerical range is confusing for most people because it’s too large. How do you determine if you’re at a 9 or 10? If you’re like most people, you can’t without a significant amount of practice.
  2. Studies show that heart rates can vary quite a bit person to person at the same workout intensity.
  3. People can have very different heart rates at the same workout intensity, leading to misestimations of RPE.

All that is why researchers eventually developed a more universally practical RPE scale known as the CR10 RPE scale, which can be used for easily estimating the intensity of all kinds of exercise.

(The CR stands for “Category-Ratio scaling,” which refers to a bunch of scientific calculations we don’t need to get into).

There are a few different versions of this RPE scale floating around, but they’re all more or less the same:

rpe scale

This new RPE scale is simpler to use and easier to understand, and it isn’t based on heart rate, which makes it more useful for strength athletes.

For example, a 0 on the CR10 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 (1RM) on your bench press.

Recommended Reading:

Is Getting Stronger Really the Best Way to Gain Muscle?

Why Do People Use RPE Scales?

The main reason people use RPE scales is to control their workout intensity.

In the context of weightlifting, this means controlling how much weight you put on the bar relative your 1RM, which is a major component of progression, as mentioned earlier.

As a natural weightlifter, here’s a maxim you take to the bank:

If you want to keep gaining muscle, you want to keep gaining strength, and the best way to do that is to keep adding weight to the bar over time.

This process is relatively simple when you first start lifting weights.

Every week, you just keep adding 5 to 10 pounds to your compound lifts, and you just keep getting bigger and stronger.

After your “newbie gains” are exhausted, however, things slow down. Gone are the days of easy progression, and if you don’t have a feasible plan for moving ahead, you’ll wind up stuck in a rut.

(Been there, done that.)

A major part of that plan needs to be incorporating RPE into your strength workouts, because it gives you a simple, reliable, and scientific way to decide how hard you’re going to push yourself to progress.

In other words, it 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 . . .

For most of us, most of these things remain fairly stable, even if undesirably so, which is why many workout programs have you add weight on a regular schedule based on a percentage of your 1RM or an arbitrary amount like 5 or 10 pounds.

This kind of “linear progression,” as it’s called, is the basis for many of the best strength training programs around. You’ll find some version of it in beginner programs like Starting Strength, intermediate programs like Wendler 5/3/1, and advanced programs like Sheiko.

There’s one problem with this approach, though: actual progress is never perfectly linear. In anything in life, let alone weightlifting.

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 have to even 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 pushing yourself to your limits?

RPE helps you make smart decisions in situations like these, because it gives you another criterion to use 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 or running into symptoms related to overtraining.

How do you do it, though? Keep reading to find out.

Recommended Reading:

The Definitive Guide to Strength Training: How to Get Strong…Fast

For Weightlifters: A Better Way to Think About RPE

how to calculate rpe

We recall that the original RPE scale was developed for endurance athletes and doesn’t work as well for weightlifting, which is probably why you’re here.

The updated CR10 scale is better for our purposes than the original scale, but it’s still not ideal for strength training because studies show that people have trouble connecting their subjective ratings with objective levels of exertion.

For example, many people will rate a set as a 9 RPE but stop several reps shy of failure based on 1RM calculations.

To understand why, we need to take another look at how the original RPE scale was developed.

Typically when RPE is used for endurance training, it’s also tied to another objective number like wattage in cycling, heart rate in running, or pace in swimming, which is referred to as “anchoring.”

For example, if your current maximum heart rate is 200 beats per minute while running, you can “anchor” that as your 10 RPE and work backwards from that to figure out what a 9, 8, and 7 should feel like.

In this case, you could say that a “7” is 70% of your maximum heart rate, which would be about 140 beats per minute. Then, during your workouts, you could use a heart rate monitor to get an accurate idea of what a 7 RPE feels like.

Train long enough and you will inevitably have good and bad days where your heart rate is lower or higher than your RPE would indicate, but research shows this method is generally reliable.

What are us weightlifters supposed to use, though?

Well, let’s start with a little exercise:

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 have done, but didn’t, and if you’re like most people, this is how you naturally talk about your weightlifting sets.

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

In other words, Reps In Reserve, is how we naturally express how hard a set feels, which is why research shows it’s a very accurate way to track the same variable as RPE (intensity).

In fact, RIR and RPE are so interchangeable that they correlate nicely with each other, like this:

rpe rpi scale

As you can see, 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.

This raises a question, though: how can you know how many reps you still have in reserve? Do you have to periodically take sets to absolute failure?

Scientists at the University of Sydney wanted to find an answer this question, so they conducted a study on 17 male bodybuilders back in 2012.

The researchers had the subjects do 5 sets of the squat and bench press. After the 10th rep of each set, everyone called out their estimated RPE and RIR, and then continued to do as many reps as they could until they reached failure.

What the scientists found is while the subjects’ RIR predictions weren’t perfect, everyone was able to predict how many reps they had left to within about 1 rep.

That is, if they predicted they could get 5 more reps, they would usually get 4 to 6 more reps when actually going for it.

The researchers also found that if the lifters used just the traditional RPE scale of 1 to 10, their predictions weren’t as accurate as when they used RIR.

Other studies have echoed these findings: RIR is a simple and more accurate and reliable way for weightlifters to estimate how hard they’re working than RPE scales.

That said, nothing is perfect, and there are 3 things to keep in mind when using RIR in your training.

1. If you have less than a year of lifting under your belt, your RIR predictions will probably be spotty.

Many people need a few years of heavy weightlifting to get good at estimating their RIR.

You can probably shorten this runway to proficiency to 6 to 12 months if you’re particularly attentive to RIR or track and test it frequently, but expect inaccuracy for the first year or so. This is why many good strength training programs prescribe regular increases in weight on the bar regardless of RPE or RIR.

2. The further you are from failure on each set, the less accurate RIR becomes.

For example, let’s say you could squat 250 pounds for five reps, and you have 200 pounds on the bar. At the fifth rep, you might estimate that you could do five more reps before failing, 1RM calculations would say otherwise, though, indicating that you could actually get 8 or 10 more reps.

The reason for this is simple: most people underpredict how many reps they can still perform as the rep range gets larger.

That’s why RIR is most effective when you’re using relatively heavy weights (80%+ of your 1RM, 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. If you’re a “beastmode” type of person, it’s easy to tell yourself that a set felt easier than it really was so you can progress faster.

And hey, I get it—guilty as charged. This is ultimately self-defeating, though.

For example, if squatting 6 reps for 310 pounds left you completely gassed, you might want to tell yourself that you racked it at a cool RIR of 3, which means you can go for 315 for 6 in your next workout.

You probably won’t be able to, though, because your true RIR was 1. Ultimately, you’ll probably miss your reps on 315 and have to go back to 310 in your next workout and keep at it.

Recommended Reading:

How to Squat: The Definitive Guide (Plus 12 Proven Ways to Improve Your Squat!)

How to Use the RPE to Get Bigger and Stronger Faster

how to use rpe scale

Let’s take a moment to review what we’ve covered so far:

  • The reason to use RPE is controlling your workout intensity. You want to use weights heavy enough to keep making strength and muscle gains, but not so heavy that you damn near shit yourself at the end of most sets.
  • Standard RPE scales work well for endurance exercise, but they don’t work well for strength training.
  • For strength training, it’s better to estimate your RPE based on your Reps In Reserve than standard RPE scales.

There are many different ways this information can inform your workout programming, and you can find all kinds of RPE-based strength training programs that use it to determine how many sets and reps to do in workouts, how long to rest between sets, and so forth.

Fortunately, you don’t need all the complexity 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.
  2. Decide on your RPE range and translate it to RIR.
  3. Determine your starting weights.
  4. Increase the weights as fast as you can while still staying within your rep range and RPE limits.

Let’s break that down step-by-step.

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 the 4-to-6 rep range for compound exercises, and 4-to-6 to 8-to-10 rep ranges for most isolation exercises.

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

Based on research from scientists like Dr. Eric Helms (a member of our scientific advisory board), a safe and effective RPE range for gaining muscle and strength is 7 to 9, which means an RIR of 3 to 1 reps.

In other words, you end most of your weightlifting sets 1 to 3 reps shy of failure.

Studies show this is a sweet spot of sorts for maintaining the proper intensity in your workouts without going to failure too often, which limits how many total reps and sets you can do in your workouts and, in some cases, increases the risk of injury.

3. Determine your starting weights.

First, use this calculator to determine your current rep maxes on the exercises you’ll be doing:

The Legion One-Rep Max Calculator

% of 1RM Weight Estimated reps
100% 1
95% 2
93% 3
90% 4
87% 5
85% 6
83% 7
80% 8
77% 9
75% 10
73% 11
70% 12

For example, let’s say you can currently bench 225 pounds for 5 reps. If you enter those numbers into the calculator above, here’s what you’ll see:

one rep max rpe

To keep things simple, we’ll stick with the Brzycki formula, which estimates that you should be able to bench 210 to 223 pounds for 4 to 6 reps.

Remember, though, that these numbers assume you’re going to absolute failure in your sets, which I don’t recommend you do every workout.

Thus, if you want to work in the 4-to-6 rep range, you wouldn’t want to load the bar with ~220 pounds, because that would most likely produce an RPE of 10 and RIR of 0.

Instead, you need to lower the weight some to bring the RPE down and RIR up to the 7 to 9 and 1 to 3 ranges, respectively—the Goldilocks zone for muscle and strength gain.

To do that, all you have to do is add 3 reps to the lower and upper limits of your given rep range, and use a weight in that range.

So in this instance, as you want to work in the 4-to-6 rep range, you’d start with a weight in the range of your 7-to-9-rep max:

one rep max chart

As you can see, this works out to 192 to 202 pounds, and if it were me, I’d start in the middle with 195 pounds and see how it works out in practice.

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

And here we come back to the elegant double progression model mentioned earlier in this article.

There are only two moving parts to this system as I like to work it:

  1. Once you hit the top of your rep range for one set and are within your RPE range, you move up in weight.
  2. If you can at least hit the bottom of your rep range in your first set with the new, heavier weight, you work with that until you can hit the top of the range.

    And if you can’t get to at least the bottom of your rep range, you go back to the lighter weight and work with it until you can perform two sets at the top of your rep range, at which point your progression should be able to “stick.”

And if you’re going to follow my advice on rep ranges and RPE/RIR, here’s how this might look:

Let’s say you’re deadlifting in the 4-to-6 rep range, and on your first set of your workout, you get 6 reps of 335 with a couple reps left in the tank. Time to progress!

You then add 10 pounds to the bar, rest a few minutes, and get 4 reps. Hooray! The progression “sticks” and you now work with 345 pounds until you can pull it for 6 reps with at least 1 RIR, move up, and so on.

If, however, you only get 2 or 3 reps with 345 pounds, you drop the weight back to 335 and work with it until you can pull it for two sets of 6 reps with an RIR of 1 to 3, at which point you move back up to 345 pounds.

(Although unlikely, if you can’t get at least 4 reps this second time around, you have two options: you can decrease the weight to 340 pounds or work with 335 until you can perform three sets of 6 reps with the prescribed RPE/RIR. I prefer the former option.)

The Bottom Line on the RPE Scale

RPE scales are used to produce a numerical estimate of how hard exercise feels.

The original Borg RPE scales were designed for endurance athletes, and they aren’t as accurate or useful for weightlifters.

A better kind of RPE scale for lifters is RIR, which represents how many more reps you could have done at the end of a set.

By incorporating RIR into your programming, and your progression scheme in particular, you can maintain the optimum level of intensity in your workouts.

Specifically, by setting limits on how close you take each set to failure, you can lift heavy enough to stimulate muscle and strength gains without trying to force your body to do things that can lead to injury, plateaus, or symptoms related to overtraining.

If you’re new to RPE and RIR, it might feel awkward at first, but don’t worry, you’ll pick it up quickly, and will quickly see the benefits in your workouts. Enjoy!

If you want to learn more about the best strength training workouts for getting bigger, leaner, and stronger, then check out these articles:

The Definitive Guide to Strength Training: How to Get Strong…Fast

Should You Use Supersets to Build Muscle Faster? What 18 Studies Say

Does Blood Flow Restriction (Occlusion) Training Really Work?

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What’s your take on the RPE scale? Have anything else to share? Let me know in the comments below!