How to read the RPE chart
Find your rep count in the left column and move across to the RPE you are aiming for. The cell is the load as a percentage of your one-rep max (1RM). Five reps at RPE 8 is 81.1%: with a 200 kg squat that is 162.2 kg, or 162.5 kg on the bar.
Along a row, the percentage falls as RPE falls: the same five reps with more left in reserve need less weight. Down a column, it falls as reps rise. Each half step of RPE moves the load by 1.3 to 2.3 percentage points, more at low reps.
The chart runs on one rule: a rep left in reserve counts the same as a rep performed. That is why 5 reps @8 and 7 reps @10 share the same cell value, 81.1%: five reps with two left is a seven-rep max. Follow that diagonal and you can check most prescriptions in your head.
RPE vs RIR: one scale, counted two ways
RPE in strength training is the 1–10 effort scale Mike Tuchscherer adapted from the Borg scale and anchored to reps in reserve (RIR): how many more clean reps you could have done. RPE 10 is nothing left, RPE 9 is one rep left, RPE 8 is two. RPE 9.5 means no more reps, but you could have added a little weight.
So RIR = 10 − RPE, and the calculator shows both. "3 × 5 @8" and "3 × 5 with 2 RIR" are the same prescription. If you write in RIR and half your roster thinks in RPE, nobody has to translate.
The chart stops at RPE 6 on purpose. Four or more reps in reserve is hard to judge with any accuracy, and sets that easy are usually warm-ups anyway.
How coaches use the chart to program
The most common pattern is a top set at a target RPE followed by back-off sets. The athlete works up to a single, a triple or a set of five @8, then drops the load for volume, either by a fixed percentage or to a lower RPE.
A worked example. The program says squat 1 × 5 @8, then 3 × 5 at −8%. The athlete hits 165 kg × 5 and calls it an 8. The chart puts that set at 81.1%, so the day's e1RM is about 203.5 kg. The back-off sets go at 92% of the top set: 151.8 kg, rounded to 152.5 kg.
The top set adjusts to the day, and the back-offs are calculated from it. After a bad night's sleep the same @8 might land at 157.5 kg instead of 165; the back-offs drop with it and the block stays as written. Tracked over weeks, the top-set e1RM is also a progress marker that does not require testing a max.
The chart also converts between styles of programming. A percentage block can be rewritten in RPE and back: 4 × 6 at 75% sits close to RPE 6.5 for a lifter whose 1RM is current, which tells you that block is meant to feel easy.
Limits: what the chart cannot tell you
It is a model built on averages. Some lifters do more reps at a given percentage than the chart predicts and some do fewer, and one person's numbers often differ between the squat, the bench press and the deadlift.
High-rep cells drift the most. Past 8–10 reps, breathing, local fatigue and tolerance for discomfort matter as much as strength, so treat the 10–12-rep rows as a starting point and adjust from logged sets.
Rating RPE is a skill. Research on the RIR-based scale found that experienced lifters rate more accurately than novices, and that ratings get more accurate the closer a set is to failure. New lifters tend to stop with more reps in reserve than they think.
An e1RM from a single set is still an estimate. It is good for setting loads and for watching the trend over a few weeks.
Sources
- Tuchscherer M. The Reactive Training Manual. Reactive Training Systems, 2008 — origin of the RPE chart used here.
- Zourdos MC et al. Novel resistance training-specific rating of perceived exertion scale measuring repetitions in reserve. J Strength Cond Res. 2016;30(1):267–275.
- Helms ER et al. Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training. Strength Cond J. 2016;38(4):42–49.