One-Repetition Maximum Calculator

Calculate your theoretical one-rep max (1RM) based on your current lifting performance using multiple validated formulas.

Exercise Information

reps

1RM Result

Complete the form to view your calculation

About 1RM

The One-Repetition Maximum (1RM) is the maximum weight you can lift for a single repetition with proper form.

Essential metric for programming strength training and tracking progress.

Accuracy Guidelines

2-5 reps
Most Accurate
6-10 reps
Good Accuracy
>10 reps
Lower Accuracy

Safety Guidelines

Always warm up properly
Use a spotter for heavy lifts
Prioritize form over weight
Rest adequately between attempts

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Formulas Used:

Brzycki (1993)

Most widely used formula in strength training

1RM = w × (36 / (37 - r))
Epley (1985)

Popular in powerlifting communities

1RM = w × (1 + r/30)
Landers (1984)

Uses percentage-based calculation

1RM = (100 × w) / (101.3 - 2.67123 × r)
Lombardi (1989)

Uses power function for calculation

1RM = w × r^0.1
Mayhew (1992)

Based on percentage of 1RM

1RM = (100 × w) / (52.2 + (41.9 × e^(-0.055 × r)))
O'Connor (1989)

Simple linear formula

1RM = w × (1 + 0.025 × r)
Adams

Linear regression formula

1RM = w / (1 - 0.02 × r)
Baechle

NSCA recommended formula

1RM = w × (1 + 0.033 × r)
Berger

Exponential decay formula

1RM = w / (1.0261 × e^(-0.0262 × r))
Brown

Linear coefficient formula

1RM = w × (0.9849 + 0.0328 × r)
Wathen

Exponential formula with dual coefficients

1RM = w / (0.4880 + 0.538 × e^(-0.075 × r))

Variables: w = weight lifted, r = repetitions completed, e = Euler's number (≈2.71828)

Reference

Wikipedia - One-repetition maximum

Comprehensive information about 1RM calculation methods and strength training

View Article
Author

Dr. Beltrán J.F.