RPE vs RIR: What Are The Differences? How To Use Them?

RIR is useful for lower rep work in strength training, while RPE can be applied to broader sport applications outside of lifting

You’ll hear the terms RPE and RIR get tossed around interchangeably by powerlifting coaches and athletes, leaving beginners confused on what they are and when to use them.

So, what is the difference between RPE vs RIR? RPE and RIR are both acronyms for ways to rate the difficulty of an exercise and in some contexts, like powerlifting, can be considered the same thing. However, generally, RIR is more relevant and useful for lower rep work in strength training, while RPE can be applied to broader sport applications outside of lifting.

It’s becoming a much more common practice for strength training programs to include some element of RPE/RIR, whether it is directly in the exercise prescription or more-so as an aside or commentary to communicate how the set felt to yourself or to your coach. 

Therefore it’s important you understand exactly what it all means and how it can serve you.

In this article I will go over both RPE and RIR independently with pros, cons and how it’s used as well as go over what actually differentiates the two and whether that differentiating factor matters to you.

What Is RPE?

rpe stands for rating of perceived exertion

RPE stands for “Rating of Perceived Exertion” and originally stems from a scale created in the 70s by Gunnar Borg. The original scale ran from 6 (no exertion) to 20 (maximum exertion), which may come as a surprise to some powerlifters who are more accustomed to a 1-10 scale when talking about RPE.

Today that 6-20 scale has been changed to a 1-10 scale as well and is used in sports other than powerlifting but it did eventually inspire the RIR-based RPE approach which I discuss below.

According to researcher Dr. Eric Helms, who did is PhD dissertation on RPE training:  

“RPE can be unreliable as the descriptions are subjective. Two people may perceive things differently [therefore] researchers should use anchoring to improve reliability.” 

The anchoring he is referring to basically means giving each notch on the scale a more objective definition otherwise one person’s “6” may be another person’s “8” when in reality they both gave a similar degree of effort. Therefore, RIR is an example of “RPE anchoring” where a 9 RPE is defined by having 1 rep in reserve and RPE 8 is defined by having 2 reps in reserve.

RPE absent from RIR is most useful when looking at things like accessory work with lots of reps or on exercises that aren’t necessarily rep-based like a plank or a carry. It can be useful in letting a person have a moment to reflect on how much effort they put into a set or even be used in a prescriptive way to set an expectation for effort.

For example, if my coach tells me to do tricep extensions at an rpe 7 but then I see he increased it to rpe 8 I know that he’s looking for me to increase my intensity and effort this week but the load itself is up to my discretion. 

This is helpful because energy, motivation and strength can fluctuate so if your coach overestimates your abilities for that week you may be at risk for injury or simply just not completing the required volume. It allows you to self-regulate.

Over time you start to become more accustomed to your “internal rpe scale” but it should be stated that it can be quite difficult for novices and beginners to determine when they’ve given enough effort because it is quite subjective and they just don’t have enough experience to gauge effort reliably.

Want to get advice on programming, technique, or competing? Speak with one of our coaches.

What Is RIR?

RIR stands for repetitions in reserve

RIR stands for “repetitions in reserve” and was created by researcher Mike Tuchscherer which essentially took the concept of RPE and translated it for the lifting context in a way that made objective sense for athletes like bodybuilders and powerlifters.

In a 2012 study by Hackett et al., bodybuilders viewed RPE, as described above, differently than how many more reps they could do. Because while they went to failure on some sets they weren’t rating it as an RPE10 just because while their body couldn’t do another rep, they rather saw their effort as being submaximal and therefore not worthy of a 10. 

In this case effort was likely interpreted to be a combination of focus, energy and ability where even if you go to technical failure on a certain set, if you really weren’t putting your best foot forward with every rep you may consider it to not be an RPE10.

Therefore, for these contexts using a more RIR-based approach is likely more useful since as someone who lifts weights, you’re probably more interested in knowing how far someone is from muscular fatigue or failure. The more seasoned a lifter is the better they become at approximating this and in the end RIR becomes an objective way to implement RPE.

Key Takeaway: The pros of RIR are that it is more straightforward and less subjective than RPE; however, it is severely limited when it comes to exercises that are not rep based, for high rep exercises or for sets where rest is manipulated.

Are There Differences Between RPE vs RIR?

differences between RPE vs RIR

It’s easy to confuse the two because similarly to how a square is a rectangle but a rectangle is not a square, RIR is a measure of RPE but RPE is not a measure of RIR.

In the words of Mike Tuchscherer himself: 

“Under normal conditions, RPE and RIR are very similar. It was designed to be that way. But the further you get from these “normal conditions” of doing rep-based exercises, the bigger the difference becomes. Imagine trying to use RIR for Farmer’s Walk or a timed barbell hold. There are also more differences when training at very high reps or training under incomplete rest breaks.”

Therefore, RIR is just a more intuitive and objective way to apply the concept of RPE, but RPE covers more broad ranges of exercises within and outside of a lifting context. 

As Dr. Eric Helms told us:

“RIR without an RPE score (just gauging how many more reps you could do) is more intuitive for some, even though RIR-based RPE and raw RIR are functionally the same.”

Key Takeaway: So are they the same for your purposes as a powerlifter? Most likely yes, especially for your squat, bench and deadlift sets. Can you still use RPE without RIR, also yes, particularly with your accessory movements.

Combining The RPE & RIR Scale 

I want to introduce a new concept to you now, which is called the “RIR-Based RPE Scale”.  

The RIR-Based RPE Scale measures rating of perceived exertion, with each value on the scale defined exactly as how many reps you perceive to have in reserve. This was specifically designed for lifting weights in the low to middle rep ranges (>10) and is most practically used by strength trainees because RPE is closely tied to RIR within the resistance training context.

It runs from 1 to 10 with 10 being 0 reps in reserve and 1 hypothetically referring to having 9 reps in reserve; however, practically speaking, you are unlikely to ever rate a working set under an RPE5.

The scale is used within the powerlifting community by coaches looking to gain insight into how much more intensity their athlete can handle for the following week of training as well as estimating 1 rep max load. 

It is also used in a prescriptive way so an athlete knows how intense their set should feel that week and to not over or undershoot the expectations.

Related Article: Prilepin’s Chart For Powerlifting: How To Use It Effectively

How Does The RIR-based RPE Scale Look Like?

The RIR-based RPE scale was made to be very easy to interpret where 10 means you have fully maxed out how many reps you can do and every descending number is an additional rep away from that max.

Therefore:

  • RPE 10 – Can’t do any more reps
  • RPE 9 – Could do 1 more rep
  • RPE 8 – Could do 2 more reps
  • RPE 7 – Could do 3 more reps
  • RPE 6 – Could do 4 more reps
  • RPE 5 – Could do 5 more reps
  • … so on and so forth

I personally work with .5 ratings as well, as do many powerlifters, and this is helpful if you’re not entirely sure of how much you have left in the tank. 

So for example, I would rate something a 7.5 if I knew for certain I could do 2 more and maybe a 3rd, but I’m not entirely confident enough to give a rating of 7.

As a tip, you should aim to train most exercises in the RPE 7-9 range for optimal results. 

RPE 5-6 is most often seen during deloads and tapers leading into competition while RPE 10 is usually only seen in competition when selecting 3rd attempts, on occasional AMRAP sets or with accessories that you’re intentionally taking to failure.

For more information on training to failure check out: Do Powerlifters Train To Failure? (Not Often, Here’s Why)

Final Thoughts

For the intents and purposes of powerlifting training, RPE and RIR are the same thing. 

However, at their truest definitions they do differ, mostly based on how they can be applied. 

RPE is more of a broad umbrella term of rating perceived effort whereas RIR is an RPE inspired scale helpful to approximate proximity to muscular failure mostly used by powerlifters and bodybuilders.


About The Author

Elena Popadic

Elena Popadic has worked within the fitness industry for over 6 years, is co-host of the Squats and Thoughts podcast and trains and competes as a powerlifter. She has a BSc in Life Sciences from McMaster University, a Postgrad Certificate in Public Relations from Humber College and is currently pursuing a MSc Occupational Therapy at Western University. Connect with her on Instagram or LinkedIn.