How to Use RPE and RIR
If you've seen RPE or RIR mentioned in training programs, you might have wondered what these terms actually mean. Fortunately, the concept behind them isn’t complicated—they're simply two sides of the same coin that tell you how hard you're working during a set (or how hard a coach is asking you to work during a set).
What They Actually Mean
RPE (Rating of Perceived Exertion) answers the following question: "On a scale of 1 to 10, how hard was that set?" At first glance, this is a super subjective question, so the answer might not be meaningful since perception of effort can vary widely from person to person. The good news is that we have a more concrete way of answering it, which relates to our next concept.
RIR (Reps in Reserve) answers the following question: "When you set the weight down, how many more reps could you truthfully have done before your muscle physically couldn't perform another concentric rep?"
Notice I said "physically couldn't," not "this burns and I don't want to keep going." Failure is the point at which your muscle literally fails to perform the concentric portion of an exercise (move the weight), regardless of how much mental fortitude you summon.
RPE and RIR have an inverse relationship, meaning that when perceived effort (RPE) increases, the number of reps you have left in the tank (RIR) decreases. For this reason, we can use either RPE or RIR on our programs to the same effect. In other words, you won’t typically see both in the same program, unless it’s to teach you the system.
The RPE and RIR Scales
Here's what each step of the RPE scale means in lifting terms, and the RIR rating that correlates with each one.
RPE 10: Couldn't possibly do another rep (0 RIR)
RPE 9: Could have done exactly 1 more rep, but no more (1 RIR)
RPE 8: Could have done exactly 2 more reps, but no more (2 RIR)
RPE 7: Could have done exactly 3 more reps, but no more (3 RIR)
RPE 6: This feels like a final warmup weight (4 RIR)
RPE 5 or less: Too light to gauge accurately, ignore (5+ RIR)
Why RPE Matters for Gains
For hypertrophy (muscle growth), you need to hit a minimum of 7 RPE to trigger meaningful adaptations. Research consistently shows that anything above 4-5 reps in reserve produces significantly less muscle growth than working closer to failure.
8 RPE hits the sweet spot for most of your training. It's hard enough to stimulate growth but manageable enough that you can accumulate sufficient volume without completely destroying yourself.
9-10 RPE has its place, particularly for single-joint exercises, intensity techniques, or when you want to push specific movements. But you can't live here across all your training, as the fatigue cost is too high. This matters because we can’t just pay attention to intra-session fatigue; we also have to consider how this session’s fatigue might affect your performance in your next session.
How Rep Ranges and RPE Work Together
Here's something crucial that trips people up: on a program that asks you to do [x] sets of [x] reps at [x] RPE, the rep range and RPE prescription work together to determine your weight selection. It’s not just one or the other—you want to think about both.
Here’s an example. If your program says "10-12 reps @ RPE 8," both numbers matter, and here’s why. That same weight that gives you RPE 8 for 10-12 reps would feel much easier (maybe RPE 6) if you only did 6-8 reps with it. Conversely, if you tried to push that same weight to 15+ reps, you'd blow past RPE 8 and land somewhere around RPE 9.5-10.
This is why you can't just find your RPE 8 weight once and use it forever, as it depends entirely on how many reps you're planning to do. A weight that's RPE 8 for 5 reps might be RPE 6 for 8 reps, or RPE 9+ for 12 reps. When selecting weight, consider both variables: "What weight allows me to complete this specific rep range at this specific RPE?"
Another super cool thing is that as you train, you get stronger over time, and the RPE system automatically accounts for that. This accounting for improvement is why RPE can be advantageous to percentage-based training. You will get stronger, and your RPE for a given load lifted for a given number of reps will decrease as you improve. That’s a good thing!
When we prescribe percentages only, we have no way of knowing that you might actually be capable of lifting a lot more or, conversely, that we accidentally overshot what we thought you could do. RPE gives you the freedom to self-regulate and it essentially accomplishes the same thing as percentage-based training—progress over time—but it executes it much more flexibly.
The Limitations of RPE
Now that I’ve talked up all the benefits of RPE-based training, let’s talk about the drawback—and it’s a big one. The effectiveness of RPE-based training relies on an athlete’s ability to accurately estimate their effort. And unfortunately, few of us are as good at it as we’d like to think—even those of us who have been training for a while.
Most people significantly overestimate their RPE, especially in their first few years of training. When a newer trainee (or someone who is just new to thinking about RPE and RIR) thinks they are at 10 RPE, they often have 2-3 reps left—sometimes significantly more. As a result, a trainer may sometimes slightly overprescribe RPE, knowing that many trainees will likely land a bit shy of what’s prescribed.
When this is done, it’s not about a lack of trust in a person’s honesty or ability. It’s because accurately gauging proximity to failure is a skill that takes time to develop, and most people simply haven't pushed themselves to true muscular failure enough times to know what 1-2 reps from failure actually feels like.
But does that mean that RPE is trash and we shouldn’t use it because garbage in, garbage out? Not necessarily. In some cases, it’s more appropriate to use percentage-based training or a combination approach. But even when our self-assessment of effort is flawed, it’s not a huge deal as long as we are adding effort over time (via load, reps, range of motion, and so on).
When you think about it, even if you start out at 6 RPE thinking it’s 9, as long as you keep getting stronger, you’ll eventually hit the load that would have been a 9 RPE on that first week, and then you can continue getting stronger from there. The timeline might be longer than anticipated, but you’ll still get there eventually. Hence, we don’t have to be perfect at RPE to benefit from it.
How to Improve Your Self-Rating of Effort
Your perception of effort will improve in accuracy with practice. In the meantime, pay attention to more than just the burning sensation you get when you’ve done a lot of reps. That feeling doesn’t necessarily tell you much about how close to failure you are.
True proximity to failure involves:
Significant bar speed reduction (or dumbbell, or machine—whatever modality you’re using)
Form starting to break down slightly
The concentric (lifting the weight) portion of the lift slowing dramatically
Genuine uncertainty about completing another rep
When you are following a program that prescribes a load based on RPE, it can feel daunting at first because something like “8 RPE” feels like way less actual guidance than giving you a concrete weight to use. But you will get it with patience and practice, so don’t worry about getting it down perfectly. Start conservative, as it's better to undershoot RPE initially and build your internal calibration than to consistently overshoot and compromise your form or recovery.
Putting RPE Into Practice
Let's say your program calls for: "Warm up doing sets of 8 reps, building to a weight that feels like RPE 8 (for 8 reps)." Ahh! That sounds awfully non-specific and might leave you feeling like, “okay, what am I actually supposed to do here?” But hang in there, because here's how to approach this systematically.
Set 1: Start with just the barbell or a very light weight. This should feel like RPE 3-4—easy, just moving your joints through the movement pattern, getting some blood going, and getting a light stretch under load.
Set 2: Add some weight. You're looking for RPE 5-6 here. The movement should feel smooth, you could easily do 12-15 reps with this load. You’re starting to feel the weight, but it doesn’t feel like work yet.
Set 3: Add more weight, to around RPE 6-7. With this weight, you could definitely do 10-12 reps, meaning that 8 reps leaves you feeling like you've got 3-4 solid reps left. It’s starting to feel like work, but it’s not too hard.
Working Sets: If you add just a little bit more weight, you’ll likely be at your target weight for RPE 8. You’ll know you’re there when upon completing 8 reps, you feel like you could do exactly 2 more reps with good form—maybe a shaky third rep if someone held a gun to your head, but definitely not a clean fourth rep. Stop there and do your working sets with that weight.
Should You Maintain RPE for All Sets?
When a program prescribs “3 sets x 8 reps @ 8 RPE," does that mean that you should aim for 8 RPE on all of your sets, or just the first one? The sort-of unhelpful answer is that it depends on your preference, or the preference of the person who wrote your program.
In my case, I'm usually talking about your first working set. If you nail RPE 8 on set one and keep the same weight, I expect that your subsequent sets will naturally drift up in RPE (perhaps feeling like RPE 8.5-9). If you tried to maintain that same RPE 8 feeling, you'd likely either hit fewer reps (maybe 6-7) or need to decrease the load.
This is completely normal because fatigue accumulates between sets and your strength output decreases even with full rest periods. Ultimately, it’s not a huge deal whether you try to maintain a consistent RPE over all your sets or allow RPE to drift up. Personally, I like to start with a target RPE on the first set and expect it to drift up as I do more sets, but neither approach is right or wrong.
Final Tips on Using RPE
Here are a few more tips and tricks about how to adjust for RPE:
If it feels too easy, you probably need to add weight on your next set. For example, if you finish your set that was supposed to be 8 RPE and immediately think, "I could have done 5 more reps,” that’s a sign that you’re not using enough load.
If you barely squeezed out the final rep on the a set that was supposed to be 8 RPE and aren't 100% sure you could do another rep, you probably hit RPE 9-10 RPE and should drop the weight slightly on your next set.
If you mess up on your RPE assessment and have to change the load or reps, don’t sweat it. This is all part of the process of learning RPE. Expect that you will make mistakes. You can still count these as work sets! Once you’ve done your warmups, go ahead and count everything as a work set, even if you had to tweak the load.
Film your sets. What feels like RPE 8 to you might look like you had 4-5 reps left to an outside observer. Bar speed and form breakdown are more objective indicators than your internal perception, especially when you're learning. For example, I have done a set that I could swear was RPE 9 or 10, but then when I look back at the video, my final rep was still snappy and it didn’t look difficult to an observer. Trust that visual feedback over what your brain is telling you—your brain sometimes lies.
Wrapping Things Up
RPE and RIR are training tools, not hard-and-fast rules. They help make your training more effective by matching your effort to your actual current capabilities and daily readiness. While reasonable accuracy is an important part of getting the most out of RPE, we don’t have to be perfect. We just need to be consistent and gradually improve.
When you use RPE or RIR in your training, start conservatively. Film your sets when possible, and pay attention to objective markers like bar speed rather than only tuning into internal sensations or self-talk. Most importantly, be patient with the learning process. With consistent practice, you'll develop an internal barometer that makes your training more effective and sustainable than a rigid system.
Remember that the real power of RPE isn't in hitting exact numbers. It's in developing the self-awareness to train appropriately hard when you need to, and appropriately easy when you need to recover. This is a skill that will serve you for decades of training.
