A Guide To Using RPE and RIR In Your Training

Updated: 28th December, 2025

What follows is an excerpt from the 3rd edition of our book, The Muscle and Strength Pyramid: Training. 📘

You can see RPE and RIR in action in our free training programs:

👉 The Ripped Body Training Programs.
👉 The Muscle and Strength Pyramid Example Programs.

Volume and intensity are the primary drivers of adaptation. Together, they determine your overall training dose.

Intensity is a critical but often misunderstood training variable. Many people equate it with how sore they get or how “hardcore” a session feels. But objectively, intensity refers to two specific factors: 

1. Load — typically defined as a percentage of your one-rep max (% of 1RM)
2. Proximity to failure — commonly expressed as rating of perceived exertion (RPE) in powerlifting circles or repetitions in reserve (RIR) in bodybuilding circles. 

For hypertrophy, both volume and proximity to failure (RIR) are key. You need to train close enough to failure for the set to provide a meaningful growth stimulus, especially at lower loads.

For strength, however, your 1RM isn’t influenced by how close you are to failure in each set. Instead, specificity is the driving factor, specifically the load you use and, as we’ll explore in Chapter 4, the specificity of the movement.

The Role Of Specificity 

In the previous section, we briefly introduced the Principle of Specificity, also known as the SAID principle (Specific Adaptations to Imposed Demands). This principle states that to achieve a particular outcome, you must train specifically for that outcome. 

Strength is a specific performance adaptation. It requires specific neuromuscular adaptation, expressed through a specific skilled lift. Therefore, maximizing your strength requires a specific training stimulus: practicing the movement you want to get stronger in, with similar loads and ranges of motion. 

Hypertrophy, on the other hand, is not a performance but a physiological adaptation. It contributes to strength but isn’t itself a performance measure. Muscle growth can be achieved across a wide range of exercises and loading schemes, provided sufficient volume and proximity to failure are met. 

To apply these concepts to training for strength or hypertrophy, it’s essential to first understand the concept of intensity — both in terms of load and proximity to failure.

Measuring Intensity 

Load and proximity to failure are most commonly defined as a percentage of 1RM, and RPE and RIR, respectively. 

Percentage of 1RM

The most common way to quantify load is as a percentage of 1RM. This can be estimated from a multi-rep RM test or directly measured on an actual 1RM test. The lower the reps in the RM, the more accurate the estimation of 1RM. 

Generally, we advise estimating 1RM from a 2–5RM performance. You can then prescribe load based on a percentage of that actual or estimated 1RM: e.g., five reps with 80% of 1RM. This system is based on research in which individuals test their 1RM on a given lift, then perform an RM with percentages of that 1RM. 

The following “Repetitions Allowed Table” is created from the most up-to-date data [1]. Importantly, the number of reps allowed changes based on training experience, history, and the specific exercise in question, which is why broad ranges are used. For example, in trained lifters using loads over 85% of 1RM on free weight exercises, the lower end of the listed ranges for repetitions allowed are probably more accurate. However, to encompass what can be done on machine-based exercises and by less experienced lifters, the ranges are broader than you might see in other such tables — this makes the ranges more broadly accurate but arguably impractical.

Table 1: Repetitions Allowed Table

While useful in theory, this system has significant limitations.

Some exercises, like lateral raises, aren’t suited to 1RM testing due to their movement patterns and ambiguous end ranges. But more importantly, after you establish a 1RM, problems arise when programming with the percentages derived from it. Was your test day a good or bad day? Was fatigue low or high? Depending on the answer, 80% of 1RM might feel like 85% or like 75%. Day-to-day fluctuations in strength and fatigue mean fixed percentages can easily misrepresent the intended training stimulus. 

It gets more complicated as you progress. If your strength improves but you haven’t retested your 1RM, you’ll be training at a lower relative intensity than intended. Conversely, if your strength has regressed, the programmed load might be too heavy. So how often should you update your 1RM? That’s a tricky question, especially if you’re not regularly testing it.  

And if you thought the “repetitions allowed” ranges were already too broad to be useful, consider that they’re actually too narrow in many cases. The variation in reps people can perform at a given percentage of 1RM is surprisingly large, especially at low percentages.

Training background plays a role, as demonstrated in a study [2] where weightlifters hit a 12RM on average with 80% of 1RM on the leg press, while runners hit a 20RM. The gap at 70% 1RM was even wider, as the weightlifters managed 20 reps while the runners hit 40! You might think this issue would disappear if you just compared lifters to one another. Well, the differences are smaller, but unfortunately, they’re still impractically large. In a study measuring max back squat reps at 70% 1RM in 58 men and women with at least two years of lifting experience and at least a 1.5x and 1x bodyweight squat, respectively, 6–26 reps were performed [3]! 

These inconsistencies make rigid percentage-based programming impractical in most settings. So, while we reference percentage-based loads to give you a useful framework, we don’t use them for load prescription in our programs.

However, as we’ll discuss in the next chapter, there is utility in having a running estimation of 1RM for your main lifts to gauge progress for competitive powerlifters and experienced lifters training for strength. For now, just know there is a time and a place for estimating 1RM, even if it’s not a great tool for load prescription.

RPE and RIR

The most common way to quantify proximity to failure is via an RPE (Rating of Perceived Exertion) or RIR (Repetitions in Reserve).

In the modern fitness community, people are familiar with RPE specifically as a tool for gauging the difficulty of resistance training. But this application is a recent phenomenon. There are many RPE scales, with the first developed by Borg in 1970 for use in aerobic training [4]. In the ~40 years since its creation, the original RPE scale has been adapted for other purposes, like resistance training, which it was not initially well-suited to. 

Traditional RPE scores describe effort qualitatively — with terms like “hard” or “very hard” — rather than quantitatively in terms of how many reps were left in the tank. This works well for capturing overall session difficulty, but it’s less reliable when rating the difficulty of an individual set, especially one taken to failure.

Why? Because a set to failure may not always be perceived as maximal exertion. For example, one person’s 5RM on bench press might feel like an 8 RPE, while another lifter doing the same weight and reps may rate it a 10. Context matters: training background, exercise selection, rep range, and individual psychology all affect perceived exertion [5].

To circumvent these issues, IPF champion, renowned coach, and author Mike Tuchscherer conceptualized and popularized an RPE scale based on RIR for powerlifting in the late 2000s. This RIR-based scale is shown on the left of the table, with RPE scores inversely determined by RIR, which are shown on the right (i.e., a 9 RPE is a 1 RIR, an 8 RPE is a 2 RIR, etc.). RIR-based RPE scores are now frequently used in powerlifting. They allow lifters to flexibly “autoregulate” load. For example, rather than eight reps at 80% of 1RM, you might prescribe eight reps at 8 RPE. This allows load adjustment set-to-set to maintain the intended proximity to failure. 

More recently, using RIR alone has become popular in the bodybuilding community. This method is more direct and easily understood and, importantly, avoids the concept of “exertion” entirely. The experience at a given RIR differs based on the exercise and the number of reps performed. 

The only downside of pure RIR is that it lacks the fidelity important for powerlifting, such as the 9.5 RPE score, as powerlifters perform singles close to, but not at 1RM, in competition and training. Nonetheless, RPE and RIR are essentially interchangeable. These scores gauge proximity to failure and prevent the large discrepancies in repetitions performed by different people when programming based on a percentage of 1RM. 

Here’s how the RIR-based RPE scale works:

Table 2: RIR and RIR-based RPE

The only issue with RIR and RPE scores is that they are rated subjectively. Over or underestimation can occur, plausibly impacting adaptations to training if large enough. Fortunately, the accuracy of RIR ratings has been thoroughly tested. 

In RIR accuracy studies, lifters in a lab are motivated to train to failure with various exercises, calling out RIR between specific reps. Then, the predicted and actual number of repetitions achieved at failure are compared. In a 2022 meta-analysis of these studies [6], Halperin and colleagues reported an average underestimation of ~1 repetition in the 414 participants included. This means RIR ratings, on average, are quite accurate. 

However, gauging proximity to failure should be considered a skill, and some are better at it than others. Further, some factors impact accuracy. RIR ratings made closer to failure are a little more accurate, meaning that a 3 or 4 RIR is more likely to be underestimated compared to a 1 or 2 RIR.

Further, the higher the reps in a set, the worse the underestimation becomes. This starts to become an issue with sets of more than 12 repetitions, with RIR underestimation getting progressively worse the higher the reps in a set. This may be due to the fact that discomfort, perceived exertion, and general negative feelings are higher following high-rep sets to failure compared to moderate-rep sets [7], which is an important consideration for hypertrophy load selection, which we’ll discuss later.

Learning To Rate RPE and RIR

As mentioned earlier, accurately rating RPE or RIR is a skill, and like any skill, it improves with intentional practice. If you find yourself struggling, try these five strategies: 

1. Record your sets and review the footage. After watching your set from a side angle or profile view, rate your RIR or RPE. This gives you a more objective view of bar speed and rep quality.
2. Run a low-volume training block (3–6 weeks) where you frequently train to momentary failure. Make sure to have spotters. Doing this allows you to experience true 0 RIR/10 RPE and calibrate what that feels like.
3. Compare your rating to that of a training partner. Before discussing, rate your RPE or RIR internally. Then ask your (ideally experienced) partner what they would rate it. Comparing notes will help sharpen your judgment.
4. Hire a coach who uses RPE/RIR and request feedback on lifting videos. External feedback is incredibly helpful when learning to self-assess.
5. Test your prediction. Start with a weight you think you can do for 8–12 reps. As you approach what feels like 2 RIR (RPE 8), keep going. If you stop at rep 10 and still get to 15, you know you need more practice with estimating proximity to failure.

For those new to RIR or RPE ratings, they can be used alongside a percentage of 1RM (for lifts you have a 1RM estimation for). Some new lifters struggle with determining the initial weight to select when given a prescription like “8 reps at 2 RIR,” especially on unfamiliar exercises. 

In this case, for lifts with a 1RM estimate, you can use the Repetitions Allowed Table to give you a rough idea to get you in the right ballpark for load selection on set 1, and then adjust after rating RIR or RPE for subsequent sets. 

For example, let’s say you are prescribed squats at “3 x 8 x 70% (RIR 2–4).” On the first set, load 70% of 1RM and do eight reps. Then rate your RIR or RPE. Our advice is to do this with video assistance (looking at video footage that will help you gauge RIR based on the bar speed). 

• If you think you have 2–4 reps in reserve, you’re on target; keep the load the same.
• If you had only one rep left, it was too heavy.
• If you had five or more reps left, it was too light.

For the latter two, adjust the load on the next set. A good rule of thumb is to adjust the weight by ~4% for every rep off target [8]. So, if you were off by 2 RIR, increase or decrease the load by ~8% on the next set.

If you have found this helpful, you might be pleased to know it is just a small section taken from our best-selling Muscle and Strength Pyramid books.

Join 200,000 other readers, get your copies here.

References

1. Nuzzo, J.L., Pinto, M.D., Nosaka, K., Steele, J. Maximal Number of Repetitions at Percentages of the One Repetition Maximum: A Meta-Regression and Moderator Analysis of Sex, Age, Training Status, and Exercise. Sports Med, 2024. 54(2): p 303–21.
2. Richens, B., Cleather, D.J. The relationship between the number of repetitions performed at given intensities is different in endurance and strength-trained athletes. Biol Sport, 2014. 31(2): p. 157–61.
3. Cooke, D.M., Haischer, M.H., Carzoli, J.P., et al. Body Mass and Femur Length Are Inversely Related to Repetitions Performed in the Back Squat in Well-Trained Lifters. J Strength Cond Res, 2019. 33(3): p. 890–5.
4. Borg, G. Perceived exertion as an indicator of somatic stress. Scand J Rehabil Med, 1970. 2(2): p. 92–8.
5. Helms, E.R., Cronin, J., Storey, A., Zourdos, M.C. Application of the Repetitions in Reserve-Based Rating of Perceived Exertion Scale for Resistance Training. Strength Cond J, 2016. 38(4): p. 42–9.
6. Halperin, I., Malleron, T., Har-Nir, I., et al. Accuracy in Predicting Repetitions to Task Failure in Resistance Exercise: A Scoping Review and Exploratory Meta-analysis. Sports Med, 2022. 52(2): p. 377–90.
7. Ribeiro, A.S., Dos Santos, E.D., Nunes, J.P., Schoenfeld, B.J. Acute Effects of Different Training Loads on Affective Responses in Resistance-trained Men. Int J Sports Med, 2019. 40(13): p. 850–5.
8. Helms, E.R., Byrnes, R.K., Cooke, D.M., et al. RPE vs. Percentage 1RM Loading in Periodized Programs Matched for Sets and Repetitions. Front Physiol, 2018. 9: p. 247.