Professional 1RM calculator using the scientifically proven Landers Formula. Determine your maximum strength potential without the risk of testing your true 1RM.
Start CalculatingEnter the weight you lifted and the number of reps performed
Your one-rep max (1RM) is the maximum amount of weight you can lift for a single repetition of a given exercise with proper form. It's a crucial metric for strength training, powerlifting, and athletic performance assessment.
Rather than risking injury by testing your true 1RM, our calculator uses the scientifically validated Landers Formula to estimate your maximum strength based on submaximal lifts.
Developed in 1985 and published in the NSCA Journal, the Landers Formula is one of the most accurate methods for estimating 1RM:
This formula has been extensively tested and validated across different populations and exercises, making it the gold standard for 1RM estimation.
Always perform a thorough warm-up before attempting heavy lifts. Start with light weights and gradually increase.
When testing near-maximal weights, always have a qualified spotter present for safety.
Maintain proper form throughout the entire range of motion. Never sacrifice technique for heavier weight.
Gradually increase weight over time. Don't attempt dramatic jumps in load.
Your muscles grow during rest. Overtraining can lead to injury and burnout.
Strength training needs fuel. Inadequate protein or calorie intake hinders progress.
Egos don’t lift weights — muscles do. Start where you are, not where you want to be.
Half reps = half gains. Perform exercises through their full range for max benefit.