Calculated using standard mathematical and industry formulas.
One Rep Max (1RM) determines the maximum weight you can lift for a single repetition on exercises like bench press, squat, or deadlift. Calculated using Epley's formula (1RM = Weight × (1 + Reps / 30)), it establishes training intensity zones (70%–85%) without maxing out.
How to use this calculator?
Enter the weight lifted on a submaximal set (e.g. bench press, squat, deadlift).
Enter the number of successful, full-range repetitions performed (best results between 2 and 10 reps).
View estimated 1RM across Epley and Brzycki equations along with a complete training percentage table.
Calculations assume strict form and minimal resting between reps in the tested set.
Step-by-step calculation example
Lifting 100 kg for 5 reps → Epley 1RM = 100 × (1 + 5/30) = 116.7 kg.
Key insights to remember
Estimating 1RM from submaximal sets (3–6 reps) prevents Central Nervous System fatigue and acute lifting injury.
The Epley formula tends to be slightly more accurate for sets under 10 reps, while Brzycki is preferred for higher reps.
95% of 1RM corresponds roughly to 2 reps, 90% to 4 reps, 80% to 8 reps, and 75% to 10 reps.
How to interpret your results?
Estimated 1RM
Your 1RM represents the theoretical maximum weight you can lift for a single clean repetition with proper form.
Training Percentages
Program at 80%–85% of 1RM for strength (3–5 reps), 70%–75% for hypertrophy (8–12 reps), and 60%–65% for muscular endurance.
Expert advice & guidance
💡 Training tip: Avoid testing true 1RM attempts too frequently to prevent joint stress and neural fatigue. Recalculate your training percentages from 3–5 rep sets every 6 to 8 weeks.
Frequently asked questions
What is a One Rep Max (1RM) and how is it calculated?
One Rep Max (1RM) is the maximum weight you can lift for a single repetition. Calculated using Epley's formula: 1RM = Weight × (1 + Reps / 30).
What is a good rep range for muscle growth vs max strength?
1–5 reps target maximum strength, 6–12 reps optimize muscle hypertrophy, and 15+ reps build muscular endurance.
How to calculate training percentages from 1RM?
Multiply your 1RM by target percentage: 85% for strength (3–5 reps), 75% for hypertrophy (8–10 reps), and 65% for volume (12–15 reps).
Why is calculating 1RM safer than testing a true 1RM?
Formula estimation predicts max capacity from 3–8 rep sets, eliminating the risk of joint or muscle injury associated with maximal heavy lifts.
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