HIF LogicHIF Logic
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Free One-Rep Max Calculator 🏋️

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Epley (default, most common)

Enter a weight and reps above to see your estimated 1RM and training percentages instantly.

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The HIF Logic Free One-Rep Max Calculator estimates maximum strength capacity for any exercise using three validated formulas: Epley (1RM = W × (1 + R/30)), Brzycki (1RM = W × 36/(37-R)), and Lander (1RM = 100W / (101.3 - 2.67123R)). Supports weight in lbs and kg with instant unit conversion. Rep range limited to 1–10 for maximum formula accuracy. Output includes estimated 1RM and a complete training percentage breakdown table from 50% to 95% in 5% increments with training zone labels: Max Strength (90–95%), Heavy Strength (80–85%), Hypertrophy (70–75%), Muscle Endurance (60–65%), Active Recovery (50%). All results update live on every input change. Keywords: one-rep max calculator, 1rm calculator, bench press max calculator, calculate lifting percentages, Epley formula, Brzycki formula, Lander formula, strength training percentages, powerlifting calculator, squat 1rm, deadlift max calculator, training block percentages, gym strength calculator, how to calculate 1 rep max, 1rm without testing to failure. Free, no account required.