A 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 common measure of strength in weightlifting and is often used to determine training loads for various strength training protocols.

Our calculator uses multiple established formulas to estimate your one-rep max based on the weight you can lift for multiple repetitions. While it provides a good approximation, individual factors like training experience, muscle fiber composition, and technique can affect your actual one-rep max. For the most accurate results, use a weight that allows you to perform between 1-10 repetitions.

Testing your true one-rep max directly can be risky, especially for beginners or intermediate lifters, as it places significant stress on your muscles, joints, and central nervous system. Calculating your one-rep max based on submaximal weights allows you to estimate your strength safely while minimizing injury risk. It's also practical for regular training, as you don't need to push to your absolute limit to track progress.

The training percentages represent recommended loads for different training goals based on your estimated one-rep max. For example, if you want to focus on building strength, you would use weights that are 85-90% of your one-rep max for lower repetitions (typically 3-5 reps). For muscle growth (hypertrophy), you would use 67-75% of your one-rep max for moderate repetitions (typically 8-12 reps). These percentages help you select appropriate weights for your specific training goals without guesswork.

As you progress in your training, your strength will improve, and your one-rep max will increase. It's recommended to recalculate your one-rep max every 4-6 weeks to ensure your training loads remain appropriate for your current strength level. This helps you continue making progress and prevents training with weights that are too light relative to your improved capabilities.