🏋️ One Rep Max Calculator
Estimate your one-rep max (1RM) from a submaximal lift using the Epley and Brzycki formulas.
Your Lift
Your Result
| % of 1RM | Weight | Typical Reps |
|---|
Estimates are most accurate for sets of 10 reps or fewer. Actual max strength varies by individual fatigue, technique, and training experience.
How the One Rep Max Calculator Works
A one-rep max (1RM) is the maximum weight you can lift for a single repetition with good form. Since testing a true 1RM is fatiguing and risky, it's commonly estimated from a lighter set taken close to failure.
Formula
Brzycki: 1RM = weight × 36 ÷ (37 − reps)
Using the Percentage Table
Once you know your estimated 1RM, the percentage table shows the weight to use for different training goals — lower percentages with higher reps build muscular endurance and hypertrophy, while higher percentages with lower reps build maximal strength.
Frequently Asked Questions
Which formula is more accurate, Epley or Brzycki?
Both are widely used estimates and tend to agree closely for rep ranges under 10. Brzycki can underestimate at higher rep counts, while Epley tends to be more linear. Neither is exact — a true 1RM test is the only way to know for certain.
How many reps should I use to estimate 1RM?
Reps between 2 and 8, performed close to failure with good form, give the most reliable estimates.
Is it safe to test a true 1RM?
Testing a true 1RM carries injury risk, especially without a spotter or coaching. Most lifters and trainers prefer to estimate 1RM from a submaximal set instead.