Concept
1RM (One-Rep Max)
A 1RM (one-rep max) is the maximum weight a lifter can lift for one repetition with proper form on a given exercise.
Your 1RM represents your absolute maximum strength on a specific lift at a specific point in time. It's the standard reference value for percentage-based training programs — programs prescribe working weights as percentages of 1RM (e.g., 5×5 at 80% of 1RM).
Because testing a true 1RM carries injury risk and high CNS cost, most lifters estimate their 1RM using rep-to-1RM formulas (Epley, Brzycki, etc.) from a heavy submaximal set rather than testing directly. Calculated 1RMs are typically accurate within 3-7% of true 1RM in the 2-10 rep range.
Further reading & authoritative sources
Related terms
e1RM (Estimated One-Rep Max)
e1RM (estimated one-rep max) is a 1RM calculated from a submaximal set of any rep count using a 1RM prediction formula or RPE chart.
Training Max (TM)
Training Max is a working percentage (typically 85-90%) of true 1RM used as the base for percentage-based training prescriptions.
RPE (Rating of Perceived Exertion)
RPE (Rating of Perceived Exertion) is a 1-10 scale that describes how hard a working set was relative to true failure, where 10 means no more reps were possible and 8 means 2 reps in reserve.