1RM Calculator (One-Rep Max)

Estimate your one-rep max from a weight you lifted for multiple reps. Educational estimate.

Choose the unit you used in the gym.
The weight you lifted for reps.
Best for 1–10 reps (estimate gets rough at high reps).
Epley: 1RM = W × (1 + reps/30)
Brzycki: 1RM = W × 36 / (37 − reps)
We show both and an average.
Use estimates responsibly. Don’t attempt true 1RM without proper technique and safety.
This tool is informational only.