What is a one rep max?
A one rep max, or 1RM, is the heaviest weight you can lift for one full repetition with good technique.
How is 1RM calculated?
This calculator uses the Epley formula: 1RM = weight x (1 + reps / 30). If you enter one rep, the 1RM is the weight lifted.
When to use training percentages
Percentage targets help plan strength sessions without testing a true max every time. Heavy work often uses 80% to 95%, while lighter volume work often uses 60% to 75%.
Limitations
A formula cannot perfectly predict max strength. Fatigue, technique, exercise choice, rest time, and rep range all affect the estimate.