Enter any weight and rep count to estimate your 1RM using four proven formulas, plus a full training percentage table.
Average of four formulas
| % of 1RM | Purpose | Weight |
|---|
This calculator uses four widely-cited formulas: Epley, Brzycki, Lander, and O'Conner. Each was derived from different populations and rep ranges. The average of all four gives a more robust estimate than any single formula alone. For sets of 1–5 reps, all formulas tend to agree closely.
Your 1RM is the foundation of percentage-based programming. Strength work (90–100%) builds neural efficiency. Hypertrophy work (65–85%) maximizes muscle growth stimulus. Speed and technique work (50–65%) improves bar path and explosiveness. Most powerlifting programs run cycles from 65% up to 90–95% over 8–12 weeks.