One Rep Max Calculator

What should I know about 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.

What's the key thing to understand about 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).

What should I know about 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.

What's the key thing to understand about 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 weight indefinitely means the relative intensity keeps dropping as you get stronger.