One Rep Max Calculator

This calculator helps estimate your One Rep Max (1RM)—the maximum weight you can lift for a single repetition. Since true 1RMs are difficult to measure repeatedly, we use established mathematical formulas based on the weight and reps you provide during a set.

We incorporate several reliable methods, including Brzycki, Epley, Lander, Lombardi, and O'Conner. Each formula uses slightly different algorithms to predict your true strength potential from submaximal sets (e.g., finding your 1RM after completing 5 repetitions at 185 lbs). The tool processes these inputs and provides a range of estimates, along with a customizable load table showing suggested weights at various percentages (like 60%, 75%, or 90%) for structured training.

• Input Data: Enter the weight and reps you successfully completed.
• Output: Receive multiple predicted 1RM values and a tailored weekly loading schedule.

To maximize the utility of this calculator, integrate its data into a structured periodization model. Periodization involves cycling through different training phases (e.g., high volume/low intensity, followed by low volume/high intensity) rather than just lifting heavy every day.

When planning your week, use the load table to ensure variety: dedicate one session to strength (90%+), another to hypertrophy (70-80%), and a third to endurance (50-60%). This systematic approach prevents plateaus.

• Focus on Form: Always prioritize perfect form over hitting the calculated weight. Poor technique dramatically increases injury risk regardless of your predicted strength.
• Listen to Your Body: If recovery is poor, it's better to adjust the load table percentages down by 5% than to risk burnout or injury trying to hit a target weight.