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Strength
One-Rep Max Calculator
What it is
A 1RM calculator estimates the maximum weight you could lift for one rep, based on a weight you've lifted for multiple reps. It uses the Epley and Brzycki formulas, the two most widely validated approaches.
Why it matters
When photos show muscle definition improving but the scale barely moves, strength numbers tell the rest of the story. Tracking 1RM over time is one of the clearest signals that a body recomp is working.
Most accurate between 2–10 reps. Don't attempt a true 1RM without proper warmup, a spotter, and experience with heavy singles.
Enter weight and reps above