RPE Calculator
Convert a strength-training set into an estimated one-rep max, or plan a target load from a known 1RM. The calculator uses repetitions and RPE together, shows reps in reserve, and builds a load table from RPE 6 to 10.
| RPE | Reps in reserve | % of 1RM | Calculated load | Rounded load |
|---|
How to use the RPE calculator
Choose Set → estimated 1RM after a completed set. Enter its total weight, repetitions, and your honest rating of perceived exertion. Choose 1RM → target set load when you already have a current 1RM estimate and want a load for a specific rep-and-RPE target.
Example: 225 lb for 5 reps at RPE 9 corresponds to 83.7% of 1RM in the lookup table. Estimated 1RM = 225 ÷ 0.837 = 268.8 lb. With rounding to 2.5 lb, the displayed estimate is 270 lb.
The table below the result holds repetitions constant and compares RPE 6 through 10. This makes it easy to see how the prescribed load changes as the intended effort changes.
RPE, RIR, and the calculation
RPE is a 6–10 strength-training effort scale. RPE 10 means no additional clean repetition was available; RPE 9 means about one repetition remained; RPE 8 means about two remained. Reps in reserve (RIR) are calculated as 10 − RPE.
The calculator uses a conventional RPE percentage chart for 1–10 repetitions and half-point RPE values:
- Estimate mode: estimated 1RM = completed-set weight ÷ chart percentage.
- Plan mode: target load = known 1RM × chart percentage.
The chart is a coaching model, not a physiological law. Individual relationships between repetitions, RPE, and percentage of 1RM vary by lift, training history, tempo, technique, and fatigue.
Limits and safe use
Do not use an estimated result as a command to attempt a maximum lift. Keep technique consistent, use suitable warm-ups and safety equipment, and use a spotter or qualified coach when appropriate. Stop if you feel pain, dizziness, or unusual discomfort.
RPE is subjective. Results are most useful when you calibrate ratings over repeated training sessions. The tool is limited to 1–10 reps and RPE 6–10 because chart-based estimates become less dependable as sets move farther from maximal strength work.