Convert a 5-rep max to an estimated 1-rep max, or estimate your 5RM from a recent set, with a rep-max chart showing loads and % of 1RM.
How the 5 Rep Max Calculator Works
A five-rep maximum is the heaviest load completed for five consistent repetitions. This calculator can begin with that known value or estimate it from another low-rep set, then build a complete rep-max ladder with one formula family instead of mixing unrelated percentage rules.
Brzycki and Epley are available separately, while Average calculates both paths and averages corresponding outputs. Keeping the inverse calculation paired with its original 1RM equation makes the 5RM and every other rep-max row internally consistent.
5 Rep Max Formula
Formula: Brzycki 1RM = 5RM × 36/32; Epley 1RM = 5RM × (1 + 5/30)
After estimating 1RM, Brzycki predicts an r-rep load as 1RM × (37 − r)/36. Epley predicts it as 1RM ÷ (1 + r/30). The one-rep row is normalized to the estimated 1RM.
Choosing the Right Inputs
Choose Known 5RM only when the entered load truly represents a maximum five-repetition effort with repeatable technique. Otherwise use 5RM from a recent set and enter a challenging set of 1 to 10 reps. Select one formula consistently when tracking changes over time.
| Output | Brzycki | Epley | Average or comparison |
|---|---|---|---|
| Estimated 1RM | 225.00 lb | 233.33 lb | 229.17 lb average |
| 3RM | 212.50 lb | 212.12 lb | Nearly identical here |
| 5RM | 200.00 lb | 200.00 lb | Known anchor |
| 8RM | 181.25 lb | 184.21 lb | Formula spread grows |
| 10RM | 168.75 lb | 175.00 lb | Endurance matters more |
Understanding Your Results
Estimated 5RM leads, followed by 1RM, a 90% training max, and every rep-max load from one through ten repetitions. Average mode also exposes the two 1RM estimates so the amount of formula disagreement remains visible.
Use the ladder as a planning and comparison tool, not a promise that every listed repetition maximum will occur on the same day. Lifters can be relatively better at high or low reps, and that profile can differ by exercise.
Worked Example
A known 200 lb 5RM converts to 225.00 lb under Brzycki and 233.33 lb under Epley, averaging 229.17 lb. Starting instead from 185 lb for eight reps gives an average estimated 5RM of about 202.50 lb.
Common Mistakes
Do not call a comfortable five-rep work set a 5RM, switch formulas between check-ins, or round intermediate calculations. Use the same movement standard and apply plate rounding only to final displayed loads.
Assumptions and Limitations
Every output is an estimate based on a population equation. Accuracy changes with exercise, technique, training status, effort, fatigue, and individual repetition endurance; direct performance remains the definitive result.
Sources
Matthew Brzycki. Strength Testing—Predicting a One-Rep Max from Reps-to-Fatigue, 1993.
Dale LeSuer and colleagues. The Accuracy of Prediction Equations for Estimating 1-RM Performance in the Bench Press, Squat, and Deadlift, 1997.
Jeremy Reynolds and colleagues. Prediction of One Repetition Maximum Strength from Multiple Repetition Maximum Testing and Anthropometry, 2006.
