How to Use the One-Rep Max (1RM) Strength Calculator
-
1
Enter the weight lifted (in kg or lbs) and the number of clean repetitions completed (1 to 12).
-
2
The calculator computes your estimated 1RM using Brzycki, Epley, Lander, and Lombardi formulas.
-
3
Inspect the 1RM percentage table (95%, 90%, 85%, 80%, 75%, 70%) to plan training sets.
-
4
Review your multi-rep maximums (e.g. your estimated 3RM, 5RM, and 10RM).
Practical Example & Use Case
Common Real-World Scenario
Lifting 225 lbs for 5 clean reps on bench press yields an estimated 1RM of approximately 260 lbs (Brzycki formula).
Technical Notes & Limitations
Browser Engine Architecture
Most accurate for 1 to 10 repetitions; accuracy decreases as reps exceed 12.
Frequently Asked Questions
What is the Brzycki 1RM formula?
`1RM = Weight / (1.0278 - (0.0278 × Reps))`.