REP MAX / % CALCULATOR

How This Calculator Works

Most 1RM calculators only go one direction: weight and reps in, estimated max out. This tool adds the reverse lookup, which is often more useful for actual programming — you already know your estimated max, but you need to know exactly what weight to load the bar with for a specific rep target in next week's program.

How the Reverse Lookup Works

The calculator first averages the Epley, Brzycki, and Lombardi formulas to get a single estimated 1RM, then runs the Epley formula backward: target load = 1RM / (1 + target reps / 30). This is the same relationship used to build the percentage table, just solved for weight instead of for max.

When to Use This Over a Straight Percentage Chart

• Programming a specific rep scheme (like 4 sets of 8) and you want the exact starting weight rather than rounding from a percentage chart.
• Testing whether a planned working weight lines up with your current estimated max before you load the bar.
• Comparing how a rep target translates across different lifts using the same known-set input.

A Note on Precision

Because this calculator chains two estimates together (submax set → estimated 1RM → target load), small input errors compound. Treat the target load as a strong starting point for your first working set, then adjust up or down by feel once the bar is in your hands — not as a number to hit exactly regardless of how the reps actually feel.