1‑Rep Max Calculator by Age

🏋️ 1‑Rep Max Calculator — Estimate your maximum lift. Brzycki formula.
kg
reps
For best accuracy, use a weight you can lift 5–10 times.
75.0
kg — Estimated 1‑Rep Max
RepsEstimated Max (kg)% of 1RM
🧭 Got your 1‑Rep Max? Now see how you compare to others your age. Check your Strength Standards →
Uses the Brzycki formula. Always warm up and use a spotter when testing your true 1‑rep max.
Author: Dr. Shirley Cheung | © theshirlshirl.com

What Is a 1‑Rep Max and Why Does It Matter?

Your 1‑rep max (1RM) is the heaviest weight you can lift for a single repetition with good form. Knowing your 1RM helps you program your training — you can set loads at specific percentages for strength, hypertrophy, or endurance work. This calculator uses the Brzycki formula, one of the most accurate submaximal estimation methods, validated across multiple studies.

Enter any weight you’ve lifted and how many reps you completed. The calculator estimates your 1RM and shows what weights correspond to different rep ranges. For safety, test your true 1RM only with a qualified spotter.

Next step: see how your numbers compare to age‑ and gender‑based strength standards.