RIR
RIR (reps in reserve) is the number of extra reps you could have done at the end of a set, with good form, before reaching failure. A set of 8 that you could have taken to 10 is “8 reps at 2 RIR”. It's a simple way to measure and plan how close to failure you train.
RIR and RPE (rate of perceived exertion) measure the same thing. RPE just counts it the other way: RPE = 10 − RIR.
| RIR | RPE | In words |
|---|---|---|
| 0 | 10 | Failure. Nothing left |
| 1 | 9 | One more rep possible |
| 2 | 8 | Two more |
| 3 | 7 | Three more |
| 4+ | 6 or less | Comfortable |
Some programs and apps write targets in RIR (“3 × 8 @ 2 RIR”), and others in RPE (“3 × 8 @ RPE 8”). They mean the same thing. To turn either one into a weight on the bar, use an RPE chart with percentages of your one-rep max.
At the end of a set, before you rack the weight, ask: “If I had to, how many more clean reps could I do?” Some cues help:
Reasonably, and it gets better with practice. A review of the research found that people tend to underestimate their reps in reserve, by about one rep on average. Estimates were most accurate on sets that were already close to failure (Halperin 2022). Experienced lifters rate more consistently than beginners (Zourdos 2016). In practice, a 1–3 RIR estimate is useful, and a “5+ RIR” estimate is a rough guess.
For most people, 1–3 RIR on most sets is the sweet spot:
Save 0 RIR for exercises where failing a rep is safe, like machines, cables and dumbbell isolation work. Keep squats, deadlifts and barbell presses at 1–3 RIR.
Logging your RIR, or its RPE equivalent, is what makes this adjustable over time. It's one of the most useful fields to record when you track a workout.
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