What is the Epley formula for 1RM?

1RM = Weight × (1 + Reps/30). For example, if you lift 100 kg for 5 reps: 1RM = 100 × (1 + 5/30) = 100 × 1.167 = 116.7 kg.

How accurate are 1RM estimation formulas?

Most formulas are accurate to within ±5–10% for rep ranges of 2–10. Accuracy drops for higher rep counts (12+). Individual factors like muscle fiber type and training history also affect accuracy.

What percentage of 1RM should I train at?

90%+ is used for max strength training (1–3 reps). 75–90% for strength/power (3–6 reps). 60–75% for hypertrophy (8–12 reps). Under 60% for muscular endurance (15+ reps). These are guidelines, not rules.

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One Rep Max (1RM)

Estimate your max lift from any rep set

Learn the formula

Weight Lifted

Reps Performed

Estimated 1RM

215.8 lbs

Epley Formula

Training Percentages

100%215.8 lbs1-2 reps

95%205.0 lbs1-2 reps

90%194.3 lbs3-5 reps

85%183.5 lbs3-5 reps

80%172.7 lbs6-8 reps

75%161.9 lbs6-8 reps

70%151.1 lbs8-12 reps

65%140.3 lbs8-12 reps

60%129.5 lbs12-15 reps

Estimating Your Maximum Lift

Your one-rep max (1RM) is the maximum weight you can lift for a single complete repetition of an exercise. Knowing it helps you structure training percentages (e.g., 85% of 1RM for strength, 60–70% for hypertrophy) without actually attempting dangerous maximal loads. This calculator uses the Epley formula — one of the most validated equations for 1RM estimation.

For best accuracy, input a weight you can lift for 5–10 reps to exhaustion. Predictions become less accurate beyond 15 reps. The Epley formula (Weight × (1 + Reps/30)) slightly overestimates at very high rep counts. Other supported formulas include Brzycki, Lander, and Lombardi — compare them for a range. All calculations run locally.