RPE and Reps in Reserve
How to judge effort with RPE and reps in reserve, autoregulate your training with them, and avoid the mistakes almost every beginner makes with both.
In short
- RPE puts a number on how hard a set was, and in strength training that number is anchored to something concrete: how many more repetitions you could have done.
- RPE and reps in reserve are one scale read from opposite ends — ten minus the RPE gives you the reps left, so "3 × 8 at RPE 8" and "3 × 8 leaving 2 in reserve" are the same instruction.
- Training to failure is a tool, not a standard: for muscle growth it shows no clear advantage over stopping a few reps short, and for strength it usually costs more than it returns.
- Prescribing effort instead of weight lets a plan absorb a bad night’s sleep without being rewritten — the target stays, the load moves to meet it.
- The estimate is a skill, and almost everyone starts out thinking they are closer to failure than they are; one honest set to failure every few weeks is what recalibrates it.
On this page
What is RPE?
RPE stands for rate of perceived exertion — a number you give a set to say how hard it actually was. It is the answer to the question a training log cannot ask: the bar said 80 kg, but what did 80 kg cost you today?
The idea is old. The original version, Gunnar Borg's 6–20 scale, was built for endurance work and lines up roughly with heart rate. Strength training uses a different, simpler version: a 1–10 scale anchored not in how out of breath you are, but in how many more repetitions you could have done. That anchor is what makes it useful in a gym. "Pretty hard" is an opinion. "I had two left" is an observation.
The reason to bother is that a training plan is written weeks in advance, and your body does not read it. The same 80 kg is a different session after a bad night's sleep than after a rest day. RPE gives the plan a way to notice.
The RPE scale
The scale used for lifting runs from about 5 to 10, and each step describes a distance from failure rather than a feeling.
- 10Maximal0 reps in reserve
No more reps were possible · A true limit set — rare in a well-run plan
- 9.5Almost maximal0 reps, but more load
No more reps, could have gone slightly heavier · Top singles in strength work
- 9Very hard1 rep in reserve
One more was there, and only one · Heavy top sets, late in a block
- 8Hard2 reps in reserve
The bar slowed but stayed under control · The usual home of productive hard sets
- 7Moderately hard3 reps in reserve
Clearly working, speed still good · Volume work, technique under load
- 6Easy effort4+ reps in reserve
Comfortable, could keep going · Warm-ups, speed work, deload sets
Half-steps exist — 8.5 means "somewhere between one and two left" — and they are worth using once you are calibrated. Before that, whole numbers are honest enough.
What are reps in reserve?
Reps in reserve (RIR) is the same information said the other way round: the number of repetitions you could still have completed with good technique when you stopped the set.
Stop a set of eight and think I had three more in me — that was 3 RIR. It is a deliberately narrow question. Not how tired you are, not whether you enjoyed it, not how the last rep looked. Just: how many more, at this weight, with this technique?
Note the qualifier "with good technique". A repetition you could only have completed by heaving the bar with your back, or by cutting the range in half, is not a rep in reserve. It is a different exercise. Counting it is the most common way RIR gets quietly inflated.
Relationship between RPE and RIR
The two are a single scale read from opposite ends. RPE counts up toward the limit; RIR counts down toward it. Ten minus the RPE gives you the reps in reserve.
| RPE | Reps in reserve | What the set looked like |
|---|---|---|
| 10 | 0 | The last rep barely moved; another would have failed |
| 9 | 1 | One more was available, no question and no more than one |
| 8 | 2 | Clear slowdown on the last rep, two still in the tank |
| 7 | 3 | Working, but the bar speed never really dropped |
| 6 | 4 or more | Brisk and repeatable |
Because they carry the same information, plans use whichever reads better in context. "3 × 8 at RPE 8" and "3 × 8, leaving 2 in reserve" prescribe exactly the same session. GetMyCoach writes plans in whichever of the two makes the instruction clearest for the movement at hand.
Examples for strength training
A prescription becomes concrete the moment you attach it to a real lift.
A squat top set at RPE 8. You work up in singles or doubles, then take one set of five at a load where you finish thinking two more were there. If that turns out to be 100 kg today and 95 kg next Tuesday, the plan still worked: the target was the effort, and you hit it both times.
Volume work at RPE 7. Four sets of ten on a dumbbell press, stopping each set three reps short. The point of these sets is accumulated quality work, not a maximum. If set four drifts to RPE 9, the weight was too heavy for the job.
A deadlift day capped at RPE 8. Deadlifts punish the next few days more than most lifts, which is why plans cap them below the level they allow on a squat or a press. The cap is not caution for its own sake — it is the price of the session after this one.
Monday
5 reps at 100 kg
Finishes at RPE 8 — two reps left, exactly as prescribed
The next week
5 reps at 92.5 kg
Poor sleep, long day; 92.5 kg is what RPE 8 costs today
The target never moved. The load did, because the effort is what was prescribed.
Training to failure
Failure — RPE 10, zero reps in reserve — is a tool, not a standard. It is worth being clear about what the evidence supports, because this is where gym culture and the research are furthest apart.
For muscle growth, training closer to failure has not shown a clear advantage once the amount of hard work is comparable. Sets taken to within a few reps of failure appear to drive similar hypertrophy to sets taken all the way. For strength, stopping short is often the better bet: failure adds fatigue that degrades the following sets and the following sessions, and strength is built on repeatable quality.
Failure also costs more on some lifts than others. A set of leg presses taken to failure is uncomfortable. A set of heavy back squats taken to failure is a different proposition, both for recovery and for safety.
Most well-built plans spend the overwhelming majority of their sets between RPE 7 and 9, and reach RPE 10 rarely and deliberately — a planned test, or the last set of an isolation movement where the cost is low.
Autoregulation
Autoregulation is what RPE is for. Instead of fixing the weight and letting the effort land wherever it lands, you fix the effort and let the weight move to meet it.
In practice that looks like a top set to a target RPE, followed by back-off sets calculated from what the top set turned out to be. A good day gives you a heavier top set and heavier back-offs; a poor day gives you lighter ones. The structure of the session — the sets, the reps, the exercises, the intent — does not change at all.
Load lifted at the prescribed RPE
Wk 1
100 kg
Wk 2
102.5 kg
Wk 3
95 kg — illness
Wk 4
105 kg
This is why an effort target is more robust than a percentage of your one-rep max. A percentage is calculated from a number you tested weeks ago, under conditions you are not in today. An RPE target is measured now.
Advantages and limitations
What it does well. It travels across exercises, equipment and sports — there is no one-rep max for a dumbbell lateral raise, but there is an effort level. It adapts to the day without anyone having to rewrite the plan. It catches accumulating fatigue early: when the same load starts costing a full point more than it did, that is information, and it usually arrives before you consciously feel run down.
Where it is weaker. It is a subjective estimate, and estimates improve with practice — beginners tend to underestimate how much they had left, sometimes by several reps. Accuracy is worse far from failure, so an RPE 6 call is much rougher than an RPE 9 one. It is also less reliable on very high-rep sets, where discomfort arrives long before actual muscular failure and feels convincingly like it.
None of that makes it unusable. It makes it a skill, and like most training skills it is learned by using it and checking yourself, not by reading about it.
Common mistakes
- Rating discomfort instead of distance from failure. A set of twenty on the leg press hurts. Hurting is not the same as being one rep from failure, and treating it that way ends with the whole plan running lighter than it should.
- Counting reps you could not have done cleanly. If the extra rep needs a hitch, a bounce or half the range, it was never in reserve.
- Calling everything an 8. If every set of the week is rated 8, the scale has stopped measuring anything. Real sessions vary.
- Never verifying. Occasionally take an isolation set to genuine failure and compare the result against your estimate. That one honest data point recalibrates months of guesses.
- Using it to talk yourself down. RPE cuts in both directions. It is there to let a bad day be lighter, not to let every day be lighter.
- Chasing the number instead of the session. If the prescribed RPE 8 lands at a weight you find disappointing, the correct response is to lift that weight. The point of the tool is to tell you things you did not want to hear.
How beginners should use RPE
If you are in your first months of training, start with RIR rather than RPE, and use only three settings: easy, two or three left, and one left. Most of your work belongs in the middle one.
Expect to be wrong at first, and expect to be wrong in the same direction — almost everyone thinks they are closer to failure than they are. That is not a reason to skip the tool; it is the reason to use it, because the estimate is what improves.
A reasonable first month looks like this: keep the weight fixed, rate every set, and only add load once a set you rated "two or three left" genuinely still feels that way. You will have learned the scale and progressed at the same time, which is the whole point.
Inside GetMyCoach, effort targets are part of the prescription rather than a note at the bottom of it: your plan states how hard each working set should be, and your logged sets are what the next session's recommendation is built from. If a set comes back far from its target, that is treated as information about you — not as a deviation from the plan.
Get a plan that prescribes effort, not just weight
Answer a few questions about your training, and GetMyCoach builds a plan where every working set carries an intensity target you can actually hit on the day you are in.
Sources
- Zourdos et al. — Novel resistance training-specific RPE scale measuring repetitions in reserveJournal of Strength and Conditioning Research — the RIR-anchored 1–10 scale used throughout this guide.
- Helms et al. — RPE and velocity relationships for the back squat, bench press and deadliftJournal of Strength and Conditioning Research — on how well lifters estimate their own proximity to failure.
- Refalo et al. — Influence of resistance training proximity-to-failure on skeletal muscle hypertrophySports Medicine — systematic review with meta-analysis.
- Foster et al. — A new approach to monitoring exercise trainingJournal of Strength and Conditioning Research — the session-RPE method for tracking training load.
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