One Rep Max Calculator
Estimate one rep max from a completed set, compare Brzycki and Epley, and explore rep-load estimates in kilograms or pounds.
Strength estimates inputs
Your estimated strength profile
90 kg · estimated 1RM
Squat context · Brzycki selected
Full result table
| Repetitions | Estimated load (kg) | Share of estimated 1RM (%) |
|---|---|---|
| 1 | 90 | 100 |
| 2 | 87.5 | 97.222222 |
| 3 | 85 | 94.444444 |
| 4 | 82.5 | 91.666667 |
| 5 | 80 | 88.888889 |
| 6 | 77.5 | 86.111111 |
| 7 | 75 | 83.333333 |
| 8 | 72.5 | 80.555556 |
| 9 | 70 | 77.777778 |
| 10 | 67.5 | 75 |
| 11 | 65 | 72.222222 |
| 12 | 62.5 | 69.444444 |
Estimated strength assumes a near-maximal completed set with consistent technique. Limits are 1–12 repetitions; estimates become less dependable at higher reps. Formula disagreement is not a statistical confidence interval. Exercise selection labels the context and does not change coefficients.
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How to use One Rep Max Calculator
- Choose the exercise for the report, then enter the load and the number of completed repetitions.
- Choose Brzycki or Epley for the main result.
- The curve shows loads obtained by reversing the selected equation for 1–12 reps.
Worked example
An 80 kg set of 5 gives Brzycki 90 kg and Epley 93.333333 kg. With Brzycki selected, an estimated 8-rep load is 72.5 kg.
Formula, accuracy & limitations
For more than one rep: Brzycki 1RM = load × 36 / (37 − reps); Epley 1RM = load × (1 + reps / 30). A one-rep set is returned as the entered load for both. Rep-load curves invert the selected equation.
Estimated strength assumes a near-maximal completed set with consistent technique. Limits are 1–12 repetitions; estimates become less dependable at higher reps. Formula disagreement is not a statistical confidence interval. Exercise selection labels the context and does not change coefficients.
These outputs use the stated model and your supplied inputs. A mathematically consistent model can still differ from personal measurements. Scenario curves and formula comparisons are not statistical confidence intervals.
Read the research and method reference ↗Enter one completed set
Choose the exercise for the report, then enter the load and the number of completed repetitions. Keep the load unit consistent, including any bar weight. A set stopped well before fatigue may underestimate strength because these equations relate repetitions to a maximal effort.
Compare the two estimates
Choose Brzycki or Epley for the main result. Both outputs remain visible, along with their numerical difference. Agreement does not prove the estimate is correct for a specific lifter or exercise. A completed one-repetition set is displayed directly instead of being inflated.
Explore the rep-load curve
The curve shows loads obtained by reversing the selected equation for 1–12 reps. These are mathematical equivalents, not a workout prescription or instructions to attempt a maximum. Warm-up, supervision, technique and available equipment remain outside the model.
Frequently asked questions
Does choosing squat change the equation?
Exercise selection changes the report context only. These general equations do not contain exercise-specific coefficients.
Should I use kilograms or pounds?
Either unit works when the load is entered in that unit. Changing the selector changes the interpretation of the number; it does not automatically convert the number you typed.
Why do the formulas disagree?
They use different relationships between repetitions and maximal load. Their difference helps you see method sensitivity, but is not a measured error margin.
Does this replace the training percentage calculator?
This tool estimates a maximum from a set. Training percentages start with a maximum you already know or choose, so the two tools answer different questions.
