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 to reps in reserve (RIR): RPE 8 means two more reps were left, RPE 9 means one. It describes effort independently of the weight, so 80 kg × 5 at RPE 7 and the same set at RPE 9.5 read as two different days in a log.
Weight and reps say what you did. RPE says what it cost. 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. RPE is the shorthand that captures the difference in one digit.
How it works
The scale runs from 1 to 10 and is anchored at the top: 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 of the scale, 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 |
A worked example. A lifter benches 80 kg for 5 and stops with two clean reps left. That set is RPE 8. The next week the same 80 kg × 5 ends with one rep left: RPE 9. Weight and reps are unchanged, but the log now records that the set got harder, which the numbers alone would have hidden. The week after, 80 kg × 5 feels like three reps were left: RPE 7, and it is time to add weight.
The scale has two histories. 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 rather than heart rate.
Why it matters for your log
Weight and reps are the objective half of a set; RPE is the subjective half, and both are needed to read the log correctly.
It explains stalls. Three weeks of 100 kg × 5 looks flat on a chart. With RPE attached it might read 9, 8, 7, which is a lift getting easier and about to move, or 8, 9, 10, which is a lift about to miss. Same numbers, opposite decisions.
It guides the next weight. Programs written in RPE, such as "5 reps at RPE 8", let the load adjust to the day. On a good day RPE 8 is 85 kg; on a bad one it is 77.5 kg. The prescription stays honest without a formula.
It keeps estimated 1RM honest. Every 1RM formula assumes the set was near failure. An 80 × 8 at RPE 6 with four reps left predicts a much lower max than the same set at RPE 10, and knowing which one you logged tells you how much to trust the estimate.
Common mistakes
- Rating every set 10. If every set was maximal, the number carries no information and fatigue arrives early. Most working sets should sit at 7 to 9.
- Rating before the set. RPE is a description of what happened, given after the last rep, not a plan for how hard to try.
- Guessing on long sets. Reps in reserve are easy to judge at 2 to 8 reps and hard at 15 or more. Past a dozen reps, take the rating with a grain of salt.
- Rounding down to look strong. An honest RPE 9 that becomes RPE 7 on paper leads to a weight jump the next week that misses. The log only works if the rating is true.
- Skipping it on the top set. If you record RPE anywhere, record it on the heaviest set of the exercise. That is the one the decisions come from.
Strongbro's estimated 1RM, personal records and ready-to-progress list are computed from weight and reps, so RPE is the judgement you bring to the next weight rather than something the app needs from you; the progress-tracking guide shows how the two fit together in a weekly review. Related terms: progressive overload, training volume, and the full glossary.
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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 being meaningful. Most lifters think in RIR and write RPE.
Is RPE accurate?
Accurate enough to be useful, and better with practice. Trained lifters judge reps in reserve within about one rep on sets taken close to failure, and drift further on lighter, longer sets. The scale was validated for resistance training by Zourdos and colleagues in 2016; 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 number times 10 roughly matched heart rate. The 1-to-10 lifting version is a later adaptation tied to reps in reserve instead of heart rate. If a program says RPE 8, it almost always means the 10-point lifting scale.
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 sets are kept for occasional tests or the last set of an exercise, because going 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 reps. 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. The rating turns a vague sense of ease or strain into a decision.
What this is based on
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