Essentials.Fitness

1RM calculator

Calculate your One Rep Max (1RM) using the Epley formula. Determine optimal training weights for 1–12 reps from your submaximal weight.

Note: This calculation is only a rough estimate and does not replace individual advice.
How does the calculator work?
  1. Enter the weight you lifted
  2. Enter the number of clean repetitions
  3. Read your estimated 1RM
  4. Use the table for optimal training weights

The calculator uses the Epley formula: 1RM = Weight × (1 + Reps / 30).

What is the 1RM (One Rep Max)?
The 1RM is the maximum weight you can lift exactly once with proper form for a given exercise. It serves as a reference value for training planning.
How accurate is the calculation?
The Epley formula provides good estimates for 1-10 repetitions. With higher rep counts, the estimate becomes less accurate. Actual max strength can vary individually.
Why should I not test my 1RM directly?
Max tests carry an increased risk of injury and require a lot of experience. Calculating from submaximal weights is safer and sufficiently accurate for training planning.
How do I use the table for my training?
The table shows you the optimal weight for different rep ranges. For strength building, train with 1-5 reps; for hypertrophy, train with 6-12 reps.
Does the 1RM apply to all exercises?
The 1RM is exercise-specific. Your bench press 1RM differs from your squat 1RM. Calculate it separately for each exercise.
How is the data calculated?

The calculator estimates your one-rep max (1RM) using the widely used Epley formula. From the lifted weight and the number of proper repetitions, it calculates your possible maximum weight for one repetition.

1RM = weight × (1 + reps / 30)

The formula provides estimates; other equations such as Brzycki or Mayhew also exist and may yield slightly different results depending on the exercise.

What studies is the calculation based on?
  • LeSuer et al. (1997)
    Key point: Compared several 1RM prediction formulas and found Epley and Brzycki to provide good estimates in untrained individuals.
    Source: Journal of Strength and Conditioning Research
  • Mayhew et al. (1992)
    Key point: Developed and validated equations to predict 1RM from submaximal repetitions.
    Source: PubMed

The actual 1RM can be influenced by technique, fatigue or daily condition. Test heavy weights only with proper safety and use the calculated values as a guideline.