One Rep Max Calculator

1RM is the most weight you can lift for one full repetition with proper form on a given lift. Strength programs use 1RM (or estimated 1RM) to set training loads as percentages, like working sets at 70 to 85 percent.

Several formulas convert a submaximal set into a 1RM estimate. Epley: weight × (1 + reps ÷ 30). Brzycki: weight × 36 ÷ (37 − reps). Lombardi: weight × reps^0.10. The calculator also offers an average of all three. None is perfect; each performs best in different rep ranges.

All three agree well for low reps (1 to 6) and diverge with higher reps. Brzycki tends to underestimate at very high reps and is undefined at 37 reps. Epley and Lombardi keep returning values at higher reps but lose accuracy. For most planning use, the average of the three is a fair pick.

Most reliable when the test set is 10 reps or fewer with crisp form. Beyond 10 to 12 reps, fatigue and technique drift make estimates noisier. Beginners should also expect more variability; max tests stabilize as form and neural adaptations improve.

Once you have an estimated 1RM, you can set working sets at fixed percentages. Hypertrophy work often sits at 65 to 80%, strength work at 80 to 95%. Peaking programs cycle higher; deload weeks pull back. Use the table as a planning starting point and adjust to perceived effort.

Direct 1RM tests are useful for experienced lifters with controlled programming. They need a spotter, thorough warm-up, and good recovery. For most people, estimated 1RM from a 3 to 8 rep set is safer and informative enough for planning.