RPE Load Calculator

Updated October 23, 2026.

How it works

The calculator uses the repetitions-in-reserve reading of the RPE scale and one equation:

1. RIR = 10 − RPE. In the repetitions-in-reserve scale, RPE 10 is no repetitions left (0 RIR), RPE 9 is about 1, and RPE 8 is about 2.
2. Repetitions you could do in total (n) = planned reps + RIR.
3. Percent of 1RM = 1 ÷ (1 + n ÷ 30), which is the Epley equation solved the other way round, and 100% when n is 1. At n = 6 this gives 83.3%, in line with the statement in the RIR-based RPE literature that about 83% of 1RM is roughly a 6-repetition maximum.
4. Working weight = 1RM × that percent, then rounded to the increment you give.

Limits, stated plainly. The published RPE chart is based on the barbell back squat and on average scores from one group of experienced lifters. Its authors say it illustrates a relationship rather than serving as an absolute conversion, that people differ in how many repetitions they can do at the same percent of their max, and that the relationship may change for machine-based, single-joint and upper-body exercises. In their own example, the standard deviation of the ratings at 8 repetitions with 70% of 1RM was 1.2 repetitions in reserve, large enough that a rating of 1 or of 5 is possible. This tool uses a formula rather than that chart, so its percentages differ slightly from published charts, especially at low repetitions. The ACSM position stand suggests taking sets near failure, around 2 to 3 repetitions in reserve, and states that there is insufficient evidence to set exact RIR or RPE targets. Training to failure is not necessary for strength or muscle gain.

Using the result by profile

For A Aim for RPE 6 to 8 while you learn the lifts. The point is clean repetitions with several left in reserve, not hitting a percent. If the calculated load feels heavy, go lighter.

For B Use RPE 7 to 9 for working sets. If the weight feels harder than planned, that is information about sleep, stress or recovery; read the readiness guide and adjust the load, not the effort.

For C Reserve RPE 9 to 10 for planned top sets and track how the same load drifts across weeks. Compare repetitions at a fixed RPE rather than chasing a number. See deloads and plateaus.

For D Teach RIR with a conversation, not a chart: ask how many more clean repetitions the client could have done, then compare with what the bar speed and form showed. Ratings improve with practice.

For E Stay within the load and effort limits set by your clinician or physical therapist, even if the calculator suggests more.

Worked example

Suppose a hypothetical one-rep max of 200 lb, and a plan of 5 reps at RPE 8. RIR = 10 − 8 = 2. Repetitions you could do in total: 5 + 2 = 7. Percent of 1RM = 1 ÷ (1 + 7 ÷ 30) = 30 ÷ 37 = 81.1%. Working weight: 200 × 0.8108 = 162.2 lb, which rounds to 160 lb with a 5 lb increment.

Two other hypothetical points show the shape: 3 reps at RPE 9 is n = 4, which gives 88.2%; 10 reps at RPE 7 is n = 13, which gives 69.8%, a long set at the edge of where the equation is used. These numbers are illustrative arithmetic, not a prescription.