What is a One Rep Max (1RM)?
Your one rep max (1RM) is the maximum weight you can lift for a single, complete repetition of a given exercise. It's the gold standard for measuring absolute strength in powerlifting, weightlifting, and increasingly in calisthenics and streetlifting.
Since actually testing your 1RM carries injury risk, these formulas let you estimate it safely from a set you can complete — typically 1–10 reps.
Understanding the Formulas
| Formula | Best For | Notes |
|---|---|---|
| Street Lifter | All exercises | Averages all formulas — most balanced estimate |
| Brzycki | 1–10 reps | Popular in powerlifting. Simple and accurate for moderate rep ranges |
| Epley | General strength | Classic formula, widely used across strength sports |
| Lombardi | Higher reps | Emphasises strength endurance |
| O'Conner | General | Similar to Epley with a smaller rep factor — slightly conservative |
| Wathan | Powerlifting | More complex exponential formula; good for wider rep ranges |
| Mayhew | Bench Press | Developed specifically for bench press, validated in research |
| Muscle-up | Muscle-ups | Specialized formula for explosive calisthenics movements |
Tips for Accurate Estimates
Use 3–6 rep sets
1RM formulas are most accurate when you reach near-failure at 3–6 reps. Higher rep sets introduce more estimation error.
Bodyweight matters for calisthenics
For pull-ups and dips your bodyweight is a core part of the total load. Enter your current bodyweight accurately — small changes affect the result.
Pick the right formula
If you're unsure, use Street Lifter (average of all formulas). For bench press use Mayhew or Wathan. For pull-ups and dips, Brzycki or Epley are most reliable.
Track it over time
Your 1RM estimate is most useful as a relative measure. Run the same calculation every few weeks to see your strength trending upward. The Calitracker app can help you.
Take Your Training Further
Log workouts, track progressions, and calculate your 1RM offline. All in one free app.