One-Repetition Maximum (1RM) Calculator
Estimate your 1RM using various popular formulas. Enter the weight you lifted and the number of repetitions.
Epley Formula
Brzycki Formula
Lombardi Formula
*These calculations are estimates. Always use caution when attempting a new 1RM.
Understanding the 1RM Formulas
The One-Repetition Maximum (1RM) is a metric used to measure the maximum weight an individual can lift for a single repetition. Estimating your 1RM from a sub-maximal set (e.g., 5-10 reps) is a safer alternative to a max-out attempt. This tool uses three of the most widely accepted formulas:
Epley Formula
The Epley formula is one of the most common and straightforward 1RM calculators. It's generally considered accurate for repetitions between 2 and 10.
1RM = Weight × (1 + Reps/30)
Brzycki Formula
The Brzycki formula is another popular method that provides a solid estimate. It's also suitable for a rep range of 2 to 10 and often yields slightly different results from Epley.
1RM = Weight ÷ (1.0278 - (0.0278 × Reps))
Lombardi Formula
The Lombardi formula is a simple power-based calculation. It's less common but still a valid tool for estimating your 1RM.
1RM = Weight × Reps0.10
Disclaimer: These calculators provide estimates. Your actual 1RM can vary due to factors like fatigue, technique, and training experience. Always warm up properly and use a spotter when lifting heavy weights.