Same idea as RPE, counted from the other end. 0 RIR is failure and equals RPE 10; 1 RIR is RPE 9; 3 RIR is RPE 7. Some coaches find clients estimate "reps left" more easily than "effort out of ten".
| RIR | RPE | What it means at the end of the set |
|---|---|---|
| 0 RIR | 10 | Failure. Another good rep was not possible. |
| 1 RIR | 9 | One more rep was left. |
| 2 RIR | 8 | Two reps left. The default for most working sets. |
| 3 RIR | 7 | Three reps left. The bar still moves quickly. |
| 4+ RIR | 6 or lower | Warm-up or technique work. |
Programs usually write a range rather than one number. 1-2 RIR on a set of 10 means choosing a weight the client could lift 11 or 12 times and stopping at 10. 0-1 RIR is failure or one rep short of it, and belongs on the last set of an isolation exercise. 2-3 RIR leaves a clear margin and suits heavy compound lifts early in a block. The RPE calculator turns any of these into a load, starting from a set the client has already done.
Most hypertrophy work sits at 1 to 3 RIR, strength work at 1 to 2, and technique or warm-up work at 3 to 4. The last few reps before failure are the ones that drive adaptation, and RIR keeps the client near them without arriving at failure on every set.
RIR is a guess and is usually guessed high. The fix is an occasional AMRAP set with the same weight: if the client thought they had 2 left and got 5, recalibrate.