Formula Information
Epley: 1RM = Weight × (1 + Reps/30) - Most popular and widely used
Brzycki: 1RM = Weight × (36/(37-Reps)) - Good for lower rep ranges
Lander: 1RM = Weight × (100/(101.3-2.67123×Reps)) - Accurate for moderate reps
Lombardi: 1RM = Weight × Reps^0.10 - Simple exponential formula
Mayhew: 1RM = Weight × (52.2 + 41.9×e^(-0.055×Reps))/100 - Research-based
O'Conner: 1RM = Weight × (1 + Reps/40) - Conservative estimate
⚠️ Safety Warning
These are estimates only. Always warm up properly, use proper form, and have a spotter when attempting heavy lifts. Consider working with a qualified trainer before attempting your actual one rep max.