Turn a completed set's weight, reps, and RPE into your estimated one-rep max for today.
| Target RPE | Weight (5 reps) |
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RPE (Rate of Perceived Exertion) describes how difficult a completed set felt on a scale commonly used from 1 to 10. RIR (Reps in Reserve) describes how many additional reps you believe you could have completed. A common strength-training convention links the two: RPE 10 means no reps left, RPE 9 means about 1 rep left, and RPE 8 means about 2 reps left. Exact RPE-to-RIR interpretation can vary between lifters and coaching systems.
Traditional percentage-based training sets a working weight from a reference such as your 1RM. RPE adds a subjective measure of how difficult the set actually feels on that day, which can help account for normal changes in performance caused by fatigue, stress, sleep, nutrition, and other factors.
RPE can therefore be used as an autoregulation tool rather than relying entirely on a fixed percentage. The appropriate load still depends on the exercise, training goal, individual lifter, and programmed effort level.
This tool uses the RTS (Reactive Training Systems) RPE-to-percentage chart associated with Mike Tuchscherer rather than a generic one-rep-max formula. Your completed reps and RPE are matched to the chart's corresponding percentage of 1RM, then your lifted weight is divided by that percentage to estimate your e1RM for today.
For example, if your completed set corresponds to 83.7% of 1RM, dividing the weight you lifted by 0.837 produces the estimated 1RM. Chart-based estimates and formula-based estimates can produce different results, so treat an e1RM as an estimate rather than an exact measurement.
Your e1RM can be useful for tracking changes in estimated strength without repeatedly testing a true 1RM. It can also provide a reference for percentage-based programming and help you compare performance across training sessions.
If you want to convert a known 1RM into specific percentage-based working weights, use our 1RM Percentage Calculator. For a submaximal Training Max used in programs such as 5/3/1, use our Training Max Calculator.
RPE describes how difficult a set felt, while RIR estimates how many reps were left before failure. A common convention is RPE 8 ≈ 2 RIR, RPE 9 ≈ 1 RIR, and RPE 10 ≈ 0 RIR.
RPE provides a way to account for day-to-day differences in performance and perceived effort instead of relying only on a fixed 1RM percentage.
Match your completed reps and RPE to the RTS chart's corresponding percentage, then divide the weight lifted by that percentage to estimate your e1RM.
RPE and RIR are subjective estimates, and their precision can vary with the exercise, lifter, rep range, and experience. This calculator uses a 1-10 rep range, so its chart-based result should be treated as an estimate rather than an exact measurement.