One Rep
Max Calculator
Estimate your 1RM from any set using the Brzycki formula.
Get percentage-based training loads instantly — free, no signup.
1RM = weight × 36 ÷ (37 − reps) · Brzycki
| Reps | Target weight | % 1RM | Zone |
|---|
Log & AI-analyze
your lifts
AIFitLog tracks your 1RM history automatically.
AI reviews your weekly progress and suggests what to lift next.
Free to download · App UI: English / Japanese only
Your one rep max (1RM) is the maximum weight you can lift for a single repetition with proper form. It is the standard baseline for percentage-based strength programming in powerlifting, weightlifting, and general strength training.
This calculator uses the Brzycki formula — one of the most accurate and widely used estimation methods for the squat, bench press, and deadlift. For best results, use a rep range of 1–10; accuracy decreases above 10 reps.
How to use: Enter the weight you lifted and the reps completed. The calculator returns your estimated 1RM and a full percentage-based load table to guide training intensity.