One Rep Max Calculator
Estimate your 1RM from a sub-maximal lift using six classic formulas (Epley, Brzycki, Lombardi, O'Conner, Wathan, Lander), with a percentage table.
Estimated 1RM (consensus)
114.9 kg
Per-formula estimates
Epley
116.7 kg
Brzycki
112.5 kg
Lombardi
117.5 kg
O'Conner
112.5 kg
Wathan
116.6 kg
Lander
113.7 kg
Projection table (from consensus 1RM)
| Target | Weight (kg) | % of 1RM |
|---|---|---|
| 1RM (max) | 114.9 | 100% |
| 2RM | 111.7 | 97% |
| 3RM | 108.5 | 94% |
| 5RM | 102.1 | 89% |
| 8RM | 92.6 | 81% |
| 10RM | 86.2 | 75% |
| 12RM | 79.8 | 69% |
Brzycki-derived: 1RM × (37 − reps) / 36. Useful for percentage-based programs.
Estimates are most accurate in the 3–8 rep range. Always warm up properly and use a spotter for heavy attempts.
How to use
- Enter the weight you lifted for a clean set, and the number of reps (1–12).
- Switch units between kg and lb if needed.
- Read the consensus 1RM at the top, individual formulas below, and a target-weight projection table at the bottom.
About this tool
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Lifting your actual one-rep max is risky and rarely needed — most strength programs prescribe weights as a percentage of estimated 1RM, derived from a sub-maximal set. This calculator runs your (weight × reps) through six well-known regression formulas and shows a consensus average alongside each individual estimate, so you can see how much they agree. Accuracy is best in the 3–8 rep range; above 10 reps the formulas diverge sharply and drift toward endurance, not strength. Below the estimates, a Brzycki-derived projection table converts the consensus 1RM into target weights for 1, 2, 3, 5, 8, 10, and 12 rep maxes — directly usable in percentage-based programs like 5/3/1, the Texas Method, or any RPE-style template.
Frequently asked questions
Which formula is most accurate?
There is no single winner: each formula was fitted to different lifters and lifts, and studies disagree on which tracks best at a given rep count. Showing the consensus average smooths out the individual biases.
Why does it cap at 12 reps?
All these formulas were fit on data from sets of roughly 1–10 reps. Beyond that, the relationship between reps and intensity becomes non-linear and dominated by endurance, so estimates drift fast. If you can do >12 reps with a weight, it is more of a hypertrophy or endurance stimulus than a strength one.
Should I actually test my 1RM?
Rarely. A true max attempt needs a proper warm-up, fresh CNS, a competent spotter, and ideally a coach watching your form. For most lifters, estimating from a clean 3–5RM is both safer and just as useful for program design.
Why does the projection table use Brzycki?
Brzycki's rep-to-percentage table, 1RM × (37 − reps) / 36, is one of the most widely used conventions for converting between a 1RM and lighter rep maxes. Using a single formula for every row keeps the projection consistent.
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