One Rep Max (1RM) Bench / Squat / Deadlift Calculator

Estimating a single maximum lift from a multi-rep set

Lifting 185 lb for 5 reps estimates a one-rep max of 215.83 lb using the Epley formula, with a suggested 90%-of-1RM training weight of 194.25 lb for lower-rep strength work.

The Epley formula is: weight x (1 + reps/30) = 185 x (1 + 5/30) = 185 x 1.1667 = 215.83 lb. It's built on the observed relationship that lifting less weight for more reps corresponds to a predictable, if approximate, higher theoretical single-rep maximum -- the formula extrapolates from a real, safer multi-rep set rather than requiring an actual (riskier) single all-out attempt.

90% of the estimated 1RM (194.25 lb) is a commonly referenced training percentage for low-rep strength work (typically 1-3 reps) -- a practical, more conservative number to actually load on the bar than attempting a true 100% single, which the Epley estimate itself is not a guarantee you could safely lift.

Why this estimate has real limits

Epley: weight x (1 + reps/30). Warm-up quality is not scored. The Epley formula (and similar 1RM formulas) become progressively less accurate at higher rep counts -- it's reasonably reliable in the 1-10 rep range, but a set of 20+ reps extrapolated through this formula tends to overestimate true 1RM meaningfully, since the relationship between reps and max strength isn't perfectly linear across the full range.

This assumes the 5-rep set was taken close to genuine muscular failure with good form -- a set stopped well short of failure (2-3 reps left in the tank) would underestimate the lifter's true 1RM, since the formula assumes the entered reps represent close to maximum effort at that weight.

Individual variation in muscle fiber type, training experience, and the specific exercise all affect how accurately any single formula predicts a true 1RM -- some lifters consistently run higher or lower than Epley's prediction, which is why several different 1RM formulas (Epley, Brzycki, Lombardi) exist and don't always agree exactly.

Using this estimate safely in training

This is a planning estimate for programming training percentages, not a substitute for an actual tested max when precision matters (like a powerlifting meet) -- treat the 215.83 lb figure as a solid guide for percentage-based programming, not a guaranteed number you could lift for a true single.

For a related bodyweight or composition metric relevant to strength training progress, the Lean Body Mass Calculator is a complementary tool.

Frequently Asked Questions (FAQ)