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One Rep Max (1RM) Calculator

Estimate your maximum lift using the Epley formula. Get a complete percentage breakdown for strength training programming.

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What is a One Rep Max?

Your One Rep Max (1RM) is the maximum amount of weight you can lift for a single repetition of a given exercise with proper form. It is the gold standard for measuring maximal strength in powerlifting, Olympic weightlifting, and general strength training.

Testing your true 1RM can be risky without proper spotters and preparation. That is why calculators like this one are so useful — they estimate your 1RM from a submaximal set, keeping you safe while still giving you the data you need for programming.

The Epley Formula

This calculator uses the Epley formula, one of the most popular and validated 1RM estimation equations:
1RM = Weight x (1 + Reps / 30)

For example, if you bench press 80 kg for 5 reps, your estimated 1RM would be: 80 x (1 + 5/30) = 80 x 1.167 = 93.3 kg.

How to Use the Percentage Table

  • 100-90% (1-3 reps): Maximal strength — longer rest (3-5 min)
  • 85-80% (4-6 reps): Strength — rest 2-4 min
  • 75-70% (6-8 reps): Hypertrophy & strength — rest 1-3 min
  • 65-60% (10-12 reps): Hypertrophy — rest 1-2 min
  • 55-50% (12-15 reps): Muscular endurance — rest 30-60 sec

Frequently Asked Questions

A One Rep Max (1RM) is the maximum amount of weight you can lift for a single repetition of a given exercise with proper form. It is the standard measure of maximal strength in weightlifting and powerlifting.
This calculator uses the Epley formula: 1RM = weight x (1 + reps / 30). This is one of the most widely used and validated formulas for estimating 1RM from submaximal lifts. It works best for sets of 1-10 repetitions.
The Epley formula provides a good estimate, typically within 5-10% of your actual 1RM for sets with 1-10 reps. For the most accurate results, use a weight you can lift with proper form for the stated number of reps. The estimate becomes less accurate with higher rep ranges.
The percentage table shows how much weight to use for different rep ranges based on your estimated 1RM. For strength: 85-100% (1-5 reps). For hypertrophy: 65-80% (6-12 reps). For endurance: 50-60% (12+ reps). Rest periods should be longer for heavier weights.

Last updated: June 2026