One Rep Max Calculator
Calculate your one-rep max using 4 proven formulas and see the full strength percentage table. Shows your 1RM for any number of reps from 1 to 12.
The Epley Formula
The Epley formula calculates 1RM as: 1RM = Weight × (1 + Reps/30). This is the most widely used formula and produces the most accurate results for 3 to 12 rep ranges. For example, lifting 80kg for 8 reps: 1RM = 80 × (1 + 8/30) = 80 × 1.267 = 101.3 kg. The Brzycki formula (1RM = Weight × 36/(37-Reps)) tends to be more accurate for very high rep counts. All one-rep max formulas are estimates — actual 1RM can vary by 5-10% due to fatigue, technique, and motivation on the day.
Training Percentage Zones
60–70% of 1RM: endurance and technique work (12–20 reps). 70–80%: hypertrophy zone (8–12 reps). 80–90%: strength zone (3–6 reps). 90–100%: maximum strength (1–3 reps).
Safety Note
Do not test your actual 1RM without proper warm-up, spotters, and experience. Most programs use calculated 1RM from submaximal lifts to set training weights safely.
Applying 1RM to Training
Your 1RM is primarily useful as a reference point for setting training loads. Common percentage schemes: 85-95% = low rep strength (1-5 reps). 75-85% = hypertrophy (6-12 reps). 65-75% = muscular endurance (15-25 reps). Research shows that taking sets to 1-3 reps from failure produces equivalent hypertrophy to working at true 1RM, while dramatically reducing injury risk. Reassess your 1RM every 4-8 weeks as strength improves and adjust training loads accordingly — working at the same absolute wei
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