1 Rep Max Calculator
Estimate your one-rep max from a set you actually lifted, averaged across six proven strength formulas — then get a full training-percentage table and rep-max targets.
A 185 lb bench for 8 reps estimates a 1RM of about 231 lb — averaged across six formulas spanning 222 lb to 236 lb.
261 lb
Estimated 1RM from a 225 lb × 5-rep set
6 formulas
Epley, Brzycki, Lombardi, Mayhew, O'Conner & Wathan — averaged
221 lb
85% training load — about 5 reps without maxing out
How to use your one-rep max
An averaged estimate, turned into working weights you can train with.
Six formulas, one estimate
Each strength formula models the rep-to-max relationship a little differently. Averaging Epley, Brzycki, Lombardi, Mayhew, O'Conner, and Wathan gives a steadier number than trusting any single equation.
Program off percentages
Your 1RM is most useful as a reference point. The training-percentage table turns it into concrete working weights — so you can run 5×5 at 80% or singles at 95% without guessing.
Lower reps, sharper estimate
The math is tightest on heavy sets of one to six reps. High-rep sets bring in endurance, so a 3–5 rep test gives a cleaner read on your true max than a burnout set.
How the 1RM Calculator Works
Formula
Epley : 1RM = w × (1 + reps/30)
Brzycki : 1RM = w × 36 / (37 − reps)
Lombardi : 1RM = w × reps^0.10
Mayhew : 1RM = 100w / (52.2 + 41.9·e^(−0.055·reps))
O'Conner : 1RM = w × (1 + reps/40)
Wathan : 1RM = 100w / (48.8 + 53.8·e^(−0.075·reps))
estimate = average of the six (w = weight, reps = reps performed)Pick your unit
Pounds or kilograms — the math is the same.
Enter the weight
The load you used for the set.
Enter the reps
How many clean reps you completed (1–10 is most accurate).
Get your 1RM
See the averaged estimate and the spread across formulas.
Train off the table
Use the percentage table and rep-max targets to set working weights.
Each formula was derived from real lifting data and predicts your max from how many reps you can do at a sub-maximal weight. They agree closely at low reps and diverge as reps climb, which is why this tool averages them and shows the full range instead of a single number.
Treat the result as a training reference, not a target to attempt blind. It's ideal for programming percentages and tracking progress over time — re-test with a fresh sub-maximal set every few weeks to see your estimate climb.
Frequently Asked Questions
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