RPE-Based e1RM Calculator
Turn a set’s weight, reps and RPE into an estimated one-rep max using the reps-in-reserve method lifters actually use.
How it works
Effective reps = reps + (10 − RPE) · %1RM = RPE chart(effective reps) · e1RM = weight ÷ (%1RM ÷ 100)
RPE (rating of perceived exertion) measures how close a set was to failure: RPE 10 is all-out, RPE 8 leaves two reps in reserve. Adding those reserve reps to the reps you actually did gives the total reps you could have hit, and a standard reps-to-percentage chart converts that into a %1RM. Dividing the weight by that percentage yields an estimated 1RM you can update from everyday working sets, without ever testing a true max.
Worked example
A set of 100 kg × 5 at RPE 8 leaves 2 in reserve, so effective reps = 5 + 2 = 7. Seven reps to failure is about 81.1% of 1RM, so e1RM = 100 ÷ 0.811 ≈ 123.3 kg.
Frequently asked questions
What is RPE in lifting?
RPE is a 1–10 scale of how hard a set felt. In strength training it maps to reps in reserve: RPE 10 means you could not do another rep, RPE 9 means one more was possible, RPE 8 means two, and so on.
How is this different from a plain 1RM calculator?
A standard 1RM calculator assumes your set was taken to failure. The RPE method accounts for sets stopped short — a 5 at RPE 8 estimates a higher max than a 5 at RPE 10, because you had more left in the tank.
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Educational training estimate, not medical or coaching advice. Individual response varies — progress under qualified supervision.