One-Rep Max Calculator
Estimate exercise-specific one-rep max using Epley, Brzycki and Lombardi formulas with a comparison range and loading table.
Estimate your one-rep max
| Formula | Estimate |
|---|
Percentage loading table
| % of estimated 1RM | Load | Open plate calculator |
|---|
What the estimate means
ToolBullet compares Epley, Brzycki and Lombardi instead of presenting one equation as exact. The spread between formulas shows model uncertainty, and repetitions above ten are flagged because fatigue resistance increasingly affects the result.
Read the formulas, comparison table and limitations.
Method reviewed 7 July 2026: peer-reviewed assessment of 1RM predictive equations and ACSM 2026 resistance-training guidance.
One-Rep Max FAQ
Which 1RM formula is most accurate?
No single equation is consistently most accurate for every exercise and person. ToolBullet shows Epley, Brzycki and Lombardi together so you can see the range rather than receiving false precision.
How many repetitions should I use for an estimate?
Lower-repetition, technically consistent sets are generally more useful. The calculator accepts up to 15 repetitions but flags more than 10 because endurance and fatigue introduce more uncertainty.
Do I need to take the set to failure?
The formulas are usually interpreted from a repetition-maximum style set. Stopping well before failure can underestimate capacity, while unsafe technique or forced repetitions can distort the result in the opposite direction.
Can I compare 1RM estimates between different exercises?
Not directly. A 1RM estimate is specific to the movement, equipment, range of motion and technique used for the input set.
Should I attempt the calculated maximum?
Not solely because a calculator displays it. A direct maximal attempt requires appropriate technique, equipment, supervision and judgement, and may be unsuitable for some people.