One-rep max calculator

How this 1RM estimate works

For sets above one repetition the calculator uses the Epley formula: estimated 1RM = weight × (1 + reps ÷ 30). A one-rep entry returns the weight itself.

The estimate stops at 12 repetitions. Higher-rep sets introduce more uncertainty, because conditioning, pacing and the exercise itself start to influence the result more than maximal strength does.

Use the result as a trend, not a command

A calculated maximum is not permission to attempt that load. Technique, equipment, fatigue, range of motion and how close the set was to failure all move the number. Compare estimates only when those conditions were reasonably similar.

What to record beside an estimated max

• The exercise and equipment variation
• The completed load and repetitions
• Whether the set used a full, consistent range of motion
• Your effort rating, such as RPE or reps in reserve
• The date, so the estimate can become a trend