About the RPE Calculator
Rate of perceived exertion (RPE) on the 1–10 lifting scale describes how hard a set was by how many reps you had left: RPE 10 is a true max, RPE 9 means one rep in reserve (RIR), RPE 8 two in reserve, and so on. This RPE calculator uses a standard RPE-to-percentage chart to estimate your one-rep max (e1RM) from any set, and then tells you the weight to load for the next prescription, such as 3 reps at RPE 9.
It is built for powerlifters and strength athletes following autoregulated programs, and for anyone who wants to estimate their max without testing it. Because RPE accounts for how the set felt, the estimate adapts to good and bad days.
The percentages come from the widely used RTS-style chart, indexed by reps plus reps in reserve and interpolated for in-between values. Chart values are averages; your own percentages may differ, especially at high reps or for lifts like the deadlift.
With the default inputs, the estimated 1rm is 123.3. Change any value above to recalculate instantly.
How to use the rpe calculator
- 1Enter the weight, reps and RPE of a recent hard set.
- 2Read your estimated 1RM and the set’s % of max.
- 3Enter the target reps and RPE from your program.
- 4Set your smallest plate jump for a ready-to-load number.
- 5Use the RPE chart to plan other sets.
Formula and method
Reps in reserve are RIR = 10 − RPE. The chart gives the percentage of one-rep max you can lift for a given number of “reps to failure” (reps + RIR): 100% for 1, 95.5% for 2, 92.2% for 3, 89.2% for 4, 86.3% for 5 and so on down to 68% for 12. Half-RPE values fall halfway between rows.
Dividing the weight you lifted by that percentage estimates your one-rep max. The target load multiplies the estimate by the percentage for the prescribed reps and RPE, then rounds to your smallest plate increment. The chart spans 1–12 reps at RPE 6–10 (up to 16 reps to failure).
- RPE
- Rating of perceived exertion, 6–10
- RIR
- Reps in reserve = 10 − RPE
- e1RM
- Estimated one-repetition maximum
Worked examples
100 × 5 @ RPE 8, planning 3 @ 9
Five reps with two in reserve means seven reps to failure, which is 81.1% of max: 100 ÷ 0.811 = 123.3 e1RM. Three reps at RPE 9 is four reps to failure, 89.2%, so the target load is 110.0.
140 × 3 @ RPE 9.5, planning 5 @ 7.5
Three reps at RPE 9.5 is 3.5 reps to failure, or 90.7%, giving an e1RM of 154.4. Five reps at RPE 7.5 (7.5 to failure) is 79.9%, which is 123.3 — rounded to 122.5 with 2.5 plates.
225 lb single @ RPE 10
A true max single is 100%, so the e1RM is 225 lb. Eight reps at RPE 8 is ten reps to failure, 73.9%, or 166.3 lb — 165 lb with 5 lb jumps.
Frequently asked questions
What does RPE 8 mean in lifting?+
RPE 8 means you could have done about two more reps with good form. RPE 9 leaves one rep in reserve, RPE 10 is a maximal effort with none left, and half-points such as 8.5 mean you might have managed one or two more.
What percentage of 1RM is RPE 8?+
It depends on the reps. A single at RPE 8 is about 92% of 1RM, a set of 5 at RPE 8 about 81%, and a set of 8 at RPE 8 about 74% according to the standard RPE chart.
Is RPE the same as RIR?+
They describe the same thing on different scales: RIR counts reps left in the tank, and RPE = 10 − RIR. RPE also allows half points and is often used for singles, where RIR is harder to judge.
How accurate is an e1RM from RPE?+
Estimates are best from low-rep sets at RPE 8–10 by lifters who rate effort accurately. High-rep sets and beginners’ ratings are less reliable, so treat the number as a training guide rather than a tested max.
Why use RPE instead of fixed percentages?+
Strength varies day to day with sleep, stress and fatigue. Loading by RPE adjusts weight to how you perform on the day, so you train hard on good days and avoid grinding on bad ones.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.