One Rep Max (1RM) Calculator
One Rep Max (1RM) is evaluated from Weight Lifted and Number of Reps Performed. The calculation reports Epley Formula 1RM, Brzycki Formula 1RM and Lander Formula 1RM.
Results
About the One Rep Max (1RM) Calculator
The calculator uses a multi formula configuration. Each reported value is read as a direct evaluation of the stored rules with the declared field formats and units.
Formula basis:
Epley: 1RM = Weight x (1 + Reps/30)
Brzycki: 1RM = Weight x 36/(37 - Reps)
Lander: 1RM = Weight x 100/(101.3 - 2.67 x Reps)
Mayhew: 1RM = 100 x Weight/(52.2 + 41.9 x e^( - 0.055 x Reps))
Interpret the outputs in the order shown by the result fields. Optional inputs affect only the outputs that depend on those variables.
Formula & How It Works
The calculation applies the following relations exactly as recorded in the metadata: Epley: 1RM = Weight x (1 + Reps/30) Brzycki: 1RM = Weight x 36/(37 - Reps) Lander: 1RM = Weight x 100/(101.3 - 2.67 x Reps) Mayhew: 1RM = 100 x Weight/(52.2 + 41.9 x e^( - 0.055 x Reps)) Each output field is produced by substituting the supplied inputs into the relevant relation and then applying the declared rounding or text format.
Worked Examples
Example 1: Bench Press — 5 reps at 225 lbs
Inputs
With Weight Lifted = 225 and Number of Reps Performed = 5 as the stated inputs, the result is Epley Formula 1RM = 262.5 same, Brzycki Formula 1RM = 253.1 same and Lander Formula 1RM = 255.8 same. Each value corresponds to the declared output fields.
Example 2: Squat — 3 reps at 315 lbs
Inputs
With Weight Lifted = 315 and Number of Reps Performed = 3 as the stated inputs, the result is Epley Formula 1RM = 346.5 same, Brzycki Formula 1RM = 333.5 same and Lander Formula 1RM = 337.7 same. Each value corresponds to the declared output fields.
Example 3: Deadlift — 8 reps at 250 lbs
Inputs
With Weight Lifted = 250 and Number of Reps Performed = 8 as the stated inputs, the result is Epley Formula 1RM = 316.7 same, Brzycki Formula 1RM = 310.3 same and Lander Formula 1RM = 312.8 same. Each value corresponds to the declared output fields.
Example 4: Overhead Press — 10 reps at 95 lbs
Inputs
With Weight Lifted = 95 and Number of Reps Performed = 10 as the stated inputs, the result is Epley Formula 1RM = 126.7 same, Brzycki Formula 1RM = 126.7 same and Lander Formula 1RM = 127.4 same. Each value corresponds to the declared output fields.
Common Use Cases
- Calculate your theoretical 1RM from a training set
- Program training weights at specific percentages of 1RM
- Track strength progress over time
- Calculate working weights for powerlifting programs