One Rep Max Calculator
By using our calculators, you agree to our Terms of Use.
Estimate 1RM from a heavy set — Epley formula with Brzycki reference.
Rates last reviewed: July 2026
Your set
Estimated 1RM
262.5
Epley · Brzycki ref: 253.2
- Epley formula
- 262.5
- Brzycki (reference)
- 253.2
Related calculators
One-rep max estimates
A one-rep max (1RM) is the heaviest weight you can lift for one repetition with good form. Testing a true 1RM is fatiguing and risky for some lifts — formulas estimate it from submaximal sets (e.g., 5 reps at 225 lb).
This calculator uses the Epley formula: 1RM ≈ weight × (1 + reps ÷ 30). It also shows Brzycki for comparison. Estimates are most accurate below ~10 reps; high-rep sets skew results.
Example: 225 lb for 5 reps → Epley 1RM ≈ 225 × (1 + 5/30) = 262.5 lb. Use 90–95% of estimated 1RM for strength programming — not medical or coaching advice.
Official sources
Rates and formulas in this calculator reference the documentation below. Confirm current numbers on the source site before relying on them. Links do not imply endorsement by those organizations of Calcometry or this tool.
Reference to CDC materials or links does not imply endorsement or recommendation by CDC, ATSDR, HHS, or the U.S. Government.
Common questions
How many reps should I use?
Most accurate between 1–10 reps. Sets above 10 reps underestimate true max because fatigue models differ.
Is this medical advice?
No. 1RM estimates are for training planning. Consult a qualified coach or clinician before maximal lifting, especially with injury history.