RIR / RPE Conversion Calculator

RIR and RPE: autoregulation in strength training

RPE (Rate of Perceived Exertion) is a 1–10 scale adapted by Mike Tuchscherer (Reactive Training Systems) from the original Borg scale to quantify effort in resistance training. RIR (Reps in Reserve) is the direct complement: how many reps remain in the tank before failure. The conversion is linear: RPE = 10 − RIR, so RPE 10 = 0 RIR (technical failure), RPE 9 = 1 RIR, RPE 8 = 2 RIR, RPE 7 = 3 RIR, and so on.

Helms et al. (2016, Strength & Conditioning Journal) validated the RIR-based RPE scale and showed strong correlation with bar velocity loss in compound lifts. It is the autoregulation tool of choice in modern powerlifting because it lets you adjust load by day-to-day fatigue: instead of a fixed %1RM, you target an RPE (e.g. “3x5 @ RPE 8”) and pick the load that puts you at that effort. This sustains volume on bad days and allows progress on good ones.

Applications

Powerlifting and weightlifting programming, daily-load autoregulation, %1RM-equivalence estimation via Tuchscherer's RPE chart, peaking plans before competition, and intensity gauges in hypertrophy programs (typical hypertrophy block: RPE 7–9; strength block: RPE 8–10).

FAQ

Are RPE and RIR the same thing? They are inverse complements. RIR counts what is left, RPE measures effort already produced. The relation is fixed: RPE + RIR = 10.

Is RPE accurate for beginners? Less so. Studies show beginners systematically underestimate RPE (think they are at 8 when they are at 6). Accuracy improves with 6–12 months of training near failure.

What is half-RPE (8.5)? Used to gauge intermediate effort, e.g. RPE 8.5 = 1–2 RIR, very common in Tuchscherer-style programming. Allows finer load progression.