One Rep Max Calculator
Estimate your 1-Repetition Maximum (1RM) for bench press, squat, or deadlift using Brzycki, Epley, and Lander formulas.
Enter Your Parameters
Understanding Your Result
The calculation generated by this tool provides an evidence-based assessment derived from established physiological and clinical equations. Use this measurement as an educational indicator alongside broader lifestyle variables, including overall dietary quality, resistance training, cardiovascular endurance, and routine medical checkups.
Mathematical Formula & Scientific Methodology
Epley Formula: 1RM = Weight × (1 + Reps / 30). Brzycki Formula: 1RM = Weight × (36 / (37 - Reps)). Both provide accurate estimations when input reps are between 1 and 10.
Step-by-Step Example Calculation
Clinical Limitations & Nuances
Formulas become significantly less accurate when input repetitions exceed 10 reps due to aerobic energy system involvement.
Frequently Asked Questions
Why estimate 1RM instead of testing a true single?
Submaximal estimation reduces the risk of joint, tendon, and muscular injury associated with maximal absolute strain.
How do I use percentage training loads?
Strength programs typically prescribe working sets at percentages of 1RM: 70-80% for hypertrophy (8-12 reps), 80-90% for pure strength (3-6 reps).
Dr. Sarah Mitchell is a Clinical Exercise Physiologist and Registered Dietitian with over 12 years of clinical research experience in human metabolism, energy expenditure, and nutritional biochemistry. She peer-reviews our calculation models and health guidelines.