RPE Calculator

Estimate 1 Rep Max and working weights based on RPE (Rate of Perceived Exertion)

Last updated: 10/8/2026

RPE, rate of perceived exertion, is the 1 to 10 scale lifters use to say how hard a set was: 10 means no more reps were possible, 9 means one rep was left, 8 means two, and so on in half-point steps. Because the scale encodes reps in reserve, a set's weight, reps, and RPE together imply a one-rep max. Enter what you lifted, how many reps, and the RPE, and the calculator estimates your 1RM and what percentage of it the set represented.

Calculator Inputs

Weight Lifted*

lbs or kg

Reps Performed*

RPE (1-10)*

Results

Enter values above to see your results

The 1RM is an estimate from a general formula and a subjective effort rating; expect errors of several percent, larger for high-rep or low-RPE sets. Do not attempt a maximal lift based solely on this number.

How It Works

Reps in reserve (RIR) = 10 − RPE. Effective reps = reps performed + RIR, the number you could have done at a true maximum effort. The estimated 1RM then comes from the Epley formula: 1RM = weight × (1 + 0.0333 × effective reps). The "effectively lifted" line is weight ÷ estimated 1RM × 100. The result is in whatever unit you entered the weight in.

How this differs from an RPE chart

Published RPE tables (such as the one popularised by Reactive Training Systems) list a percentage of 1RM for each reps-and-RPE combination, built from observed lifting data. This calculator instead converts the set to an equivalent all-out effort and applies Epley, a general rep-max formula. The two agree closely at RPE 8 to 10 for 1 to 6 reps, which is where RPE-based programming is most used. For high-rep sets or low RPEs both methods become rough, and the Epley approach tends to give slightly higher 1RMs than the charts.

Using the estimate for programming

Once you have an estimated 1RM, planned sets such as "5 reps at RPE 8" translate to a weight: 5 reps with 2 in reserve is 7 effective reps, which Epley puts at about 81% of 1RM. Re-estimate from recent working sets rather than a single old max; RPE-based training is meant to adjust load to how you perform on the day.

Worked example

Default inputs: 225 × 5 reps at RPE 8

Reps in reserve:10 − 8= 2

Effective reps:5 + 2= 7

Estimated 1RM:225 × (1 + 0.0333 × 7)= 277.4

Effectively lifted:225 ÷ 277.4 × 100= 81.1% of 1RM

Had the same set been RPE 9 (one rep left), effective reps would be 6 and the estimate 270.0; at RPE 10 it would be 262.5.

Tips & Best Practices

•RPE auto-regulates load: on a tired day the weight that feels like RPE 8 is lower, and the plan still gets completed without grinding.
•Be honest about reps in reserve; rating sets too easy inflates the 1RM estimate and every percentage built on it.
•Rate the set by the last rep's speed and effort, and compare with video if you are new to RPE; most lifters under-rate RIR at first.

Frequently Asked Questions

Why does RPE 10 with 1 rep not give exactly the weight lifted?

It does: 1 rep at RPE 10 is 1 effective rep, and Epley gives weight × 1.0333, about 3% above the weight. That is a known quirk of the Epley formula, which is calibrated for multi-rep sets. If you have a true 1-rep max, use it directly rather than estimating.

Is the estimate the same for squat, bench, and deadlift?

The formula is lift-agnostic. In practice, rep-max relationships differ by lift and lifter: many people get more reps at a given percentage on squat than on bench, so an estimate from a squat set may run a little high when applied to bench. Calibrate against your own history.

Can I use RPE below 6 or above 12 reps?

You can enter them, but the estimate becomes unreliable. Below RPE 6 lifters cannot judge reps in reserve accurately, and above roughly 10 to 12 reps endurance rather than strength limits the set, so Epley over-predicts 1RM.