Bulk Coach for iPhoneConvert lifting RPE to repetitions in reserve and estimate 1RM from load, reps and the remaining-repetition estimate.
This calculator uses the common lifting shorthand RIR = 10 − RPE, then adds estimated remaining repetitions to the completed reps for an Epley-style 1RM estimate. RPE and RIR are subjective, so the result is context rather than a measured maximum.
RPE is a subjective estimate, not a measurement.
An RPE 8 set maps to roughly two repetitions in reserve. The calculator assumes that estimate is accurate and that the set is suitable for an Epley calculation; both assumptions can be wrong.
Compare similar sets on the same exercise. Do not use a small estimated change as proof that muscle or strength changed.