Your One-Rep Max (1RM) is the maximum weight you can lift for exactly one repetition with proper form. It's crucial for designing effective training programs, tracking strength progress, and setting appropriate training loads for different goals.

Our formulas are scientifically validated and most accurate for 1-10 repetition ranges. Accuracy depends on several factors:

• • Lower rep ranges (1-6) are more accurate than higher reps
• • Your training experience and consistency
• • The specific exercise being performed
• • Your current fatigue and recovery status

Testing your true 1RM can be valuable but should be done carefully:

• • Only test when well-rested and properly warmed up
• • Always have a qualified spotter
• • Don't test more than once every 4-6 weeks
• • Consider using calculated estimates for regular training

For most training purposes, calculated 1RMs are safer and equally effective.

Yes! 1RM Calculator is completely free to use and always will be. No registration required, no hidden fees, no premium features. We believe everyone should have access to accurate strength training tools.

The calculator works best for compound movements like:

• • Bench Press, Squat, Deadlift
• • Overhead Press, Rows
• • Other multi-joint exercises

It's less accurate for isolation exercises or movements with very different strength curves.

Each formula was developed using different research methodologies and population samples. The variations reflect individual differences in strength characteristics, training background, and muscle fiber types. This is why we offer multiple formulas - to give you a range of estimates rather than a single potentially inaccurate number.