How This Calculator Helps You Estimate Your 1RM Safely

While testing your true 1RM by lifting the maximum weight you can handle is one way to determine it, it’s not always the safest or most practical method—especially for beginners or those without proper supervision. This is where our 1RM calculator becomes invaluable.

This tool uses scientifically-backed formula to accurately estimate your 1RM based on the weight you lift and the number of repetitions you perform. It goes a step further by factoring in RIR (Reps in Reserve), enhancing the precision of your estimate and ensuring the process is both safe and reliable. Whether you're looking to track your progress or plan your next workout, this calculator provides a smart, risk-free way to determine your one-rep max.

*Remember that although these calculations are scientifically-backed these are still estimates that can vary from one person to another

Why Does This Calculator Only Show Results Up to 20 Reps? 

This calculator focuses on the most reliable rep ranges (1–20 reps) to ensure accurate estimates. While 20 reps is already on the higher end of what’s considered useful for 1RM estimation, it still provides a reasonable balance between accuracy and practicality.