What Is RPE? The 1-10 Scale and Reps in Reserve | Strongbro
Quick answer
RPE, or rate of perceived exertion, is a 1-to-10 rating of how hard a set felt, where 10 means no further rep was possible. In strength training it maps directly onto reps in reserve (RIR): RPE 8 means two more reps were left, RPE 9 means one. Because it describes effort independently of the weight, 80 kg × 5 at RPE 7 and the same set at RPE 9.5 read as two very different days in a log.
RPE is a rating from 1 to 10 of how hard a set felt, given after the set is over. It records what the set cost you, which weight and reps on their own cannot. A set of 80 kg × 5 can be a warm-up for one lifter and a grinding record for another, and for the same lifter it can be either depending on the week.
The scale
The scale is anchored at the top. RPE 10 means you could not have completed another rep with good form. Each step down adds one rep you could have done. In the lifting version, that mapping is the whole definition.
| RPE | Reps in reserve | What the set felt like |
|---|---|---|
| 10 | 0 | No further rep was possible |
| 9.5 | 0 to 1 | Maybe one more, not certain |
| 9 | 1 | One more rep, no more |
| 8.5 | 1 to 2 | Definitely one, possibly two |
| 8 | 2 | Two more reps |
| 7.5 | 2 to 3 | Two, possibly three |
| 7 | 3 | Three more reps |
| 6 | 4 | Four more reps |
| 5 and below | 5 or more | Warm-up, or a light technique set |
An example across three weeks. A lifter benches 80 kg for 5 and racks it with two clean reps left: RPE 8. The next week the same 80 kg × 5 ends with one rep left, so RPE 9. Weight and reps are unchanged, and the log now records that the set got harder, which the numbers alone would have hidden completely. The week after that, 80 kg × 5 feels like three reps were left. RPE 7, and it is time to add weight.
The scale has two histories worth keeping straight. Borg's original version, published for endurance exercise, ran from 6 to 20 so that the rating times 10 tracked heart rate. The 1-to-10 lifting scale was formalised for resistance training by Zourdos and colleagues in 2016, tying each number to reps in reserve instead.
What it adds to weight and reps
Weight and reps are the objective half of a set. RPE is the subjective half, and the log reads differently with it.
Take three weeks of 100 kg × 5, which looks perfectly flat on a chart. With RPE attached it might read 9, 8, 7, which is a lift getting easier and about to move. Or it might read 8, 9, 10, which is a lift about to be missed. Same numbers, opposite decisions.
That also makes RPE useful for writing the program itself. A prescription of "5 reps at RPE 8" lets the load adjust to the day: on a good day that is 85 kg, on a bad one 77.5 kg, and the intent of the session survives either way.
There is a quieter use. Every 1RM formula assumes the set was taken near failure, so an estimated 1RM from an 80 × 8 at RPE 6 predicts a much lower max than the same set at RPE 10. Knowing which one you logged tells you how far to trust the estimate.
Rating it honestly
The failure mode is rating everything 10. If every set was maximal then the number carries no information, and the fatigue arrives early anyway. Working sets mostly belong at 7 to 9.
Rating before the set is the other error. RPE describes what happened, given after the last rep, and it is not a plan for how hard to try.
Long sets are genuinely hard to rate. Reps in reserve are easy to judge at 2 to 8 reps and much harder at 15 or more, so past a dozen reps take your own rating with a grain of salt.
The one that actually breaks the system is rounding down to look strong. An honest RPE 9 written as RPE 7 buys you a weight jump next week and a missed set to go with it. And if you only record the rating in one place, record it on the heaviest set of the exercise, because that is the set your decisions come from.
Strongbro computes estimated 1RM, personal records and the ready-to-progress list from weight and reps alone, so RPE stays the judgement you bring to the next weight rather than a field the app demands. The progress-tracking guide shows how the two fit together in a weekly review. Nearby terms: progressive overload, training volume, and the glossary itself.
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Frequently asked questions
What is the difference between RPE and RIR?
They describe the same thing from opposite ends. RIR counts the reps you had left; RPE rates the effort out of 10. RPE 10 is 0 RIR, RPE 9 is 1 RIR, RPE 8 is 2 RIR, and so on down to about RPE 5, where the rep count stops meaning much. The two terms get used interchangeably.
Is RPE accurate?
Accurate enough to be useful, and it improves with practice. Zourdos and colleagues, who validated the scale for resistance training in 2016, found ratings closest to reality on sets taken near failure, with more drift on lighter, longer ones. The underlying idea comes from Borg's work in the 1970s and 80s.
Where does the 6-to-20 RPE scale come from?
That is Borg's original scale, built for endurance exercise so that the rating times 10 roughly matched heart rate. The 1-to-10 lifting version came later and is tied to reps in reserve instead of heart rate. When a program says RPE 8, it almost always means the 10-point lifting scale rather than Borg's.
What RPE should working sets be?
Most strength and hypertrophy programs place working sets between RPE 7 and 9, which is 1 to 3 reps in reserve. RPE 10 gets saved for occasional tests or the last set of an exercise, because training to failure every set raises fatigue faster than it raises results. Warm-ups sit at RPE 5 or below.
How do I use RPE to pick the weight?
Work backwards from the target. If the program asks for 5 reps at RPE 8, choose a weight you could lift for about 7. If last week's 80 kg × 5 felt like RPE 7, a small increase is due; if it felt like RPE 9.5, hold the weight where it is. The rating turns a vague sense of strain into a decision.
What this is based on
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