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Strength calculator

RPE calculator

Convert RPE and reps into a percentage of your 1RM — and back again. Enter the set you actually did and get the load for every other effort level. Free, instant, no sign-up.

ESTIMATED 1RM
123.3kg
81.1% of 1RM · 2 reps in reserve

Same 5 reps at every RPE

RPE
% 1RM
Weight (kg)
10
86.3%
106.4
9.5
85%
104.8
9
83.7%
103.2
8.5
82.4%
101.6
8
81.1%
100
7.5
79.9%
98.5
7
78.6%
96.9
6.5
77.4%
95.4
6
76.2%
94

Every set length at RPE 8

Reps
% 1RM
Weight (kg)
1
92.2%
113.7
2
89.2%
110
3
86.3%
106.4
4
83.7%
103.2
5
81.1%
100
6
78.6%
96.9
7
76.2%
94
8
73.9%
91.1
9
71.7%
88.4
10
69.6%
85.8
11
67.6%
83.4
12
65.6%
80.9

Tell the coach how each set felt and it adjusts next week's loads for you.

What is RPE in lifting?

RPE is rating of perceived exertion on a 1–10 scale, borrowed from Mike Tuchscherer's autoregulation work. In the gym only the top of the scale matters: RPE 10 means you could not have done another rep, RPE 9 means one more was there, RPE 8 means two. The mirror of it is RIR — reps in reserve — which is simply 10 minus the RPE.

How this calculator works

The chart is one sequence read along diagonals. What sets the percentage is not how many reps you did but how many you were from failure: 3 reps at RPE 10, 4 at RPE 9, and 5 at RPE 8 are all four reps from failure, so all three sit at 92.2% of 1RM. Half-point RPEs land between two entries and take the midpoint. Divide your load by that percentage and you have an estimated max.

RPE calculator vs 1RM calculator

A standard one-rep max calculator reads effort off the rep count alone — Epley and Brzycki both assume the set went to failure, so a comfortable triple and a grinding triple return the same number. The RPE chart asks the missing question: how many reps did you leave? That makes it the better tool on days when you stopped short, and it is why the two calculators disagree on easy sets.

Programming with RPE

Percentages come from a max you tested weeks ago; RPE comes from the athlete standing in front of the bar today. Most autoregulated programs prescribe both — five reps at 80%, stop if it hits RPE 9 — so a bad night's sleep costs you load rather than a failed session. Use the second table above to find the load for a target RPE at any set length.