One-Rep Max (1RM) Calculator

What is One-Rep Max (1RM)?

One-Rep Max (1RM) is the maximum amount of weight that a person can lift for a single repetition of a given exercise. It's a crucial metric in strength training and weightlifting, used to measure an individual's maximum strength and to plan training programs.

The Brzycki Formula for 1RM Estimation

While the true 1RM can only be determined through actual testing, which can be risky, we often use formulas to estimate it. One of the most common is the Brzycki formula:

\[1RM = \frac{W \times 36}{37 - R}\]

Where:

• \(1RM\) = One-Rep Max
• \(W\) = Weight lifted
• \(R\) = Number of repetitions (should be ≤ 10 for accuracy)

Step-by-Step 1RM Calculation

1. Perform a set of an exercise with a weight you can lift for 1-10 reps
2. Note the weight lifted and the number of reps completed
3. Apply the Brzycki formula: \[1RM = \frac{W \times 36}{37 - R}\]

Example Calculation

Let's calculate the 1RM for someone who lifted 225 lbs for 5 reps:

1. \(W = 225 \text{ lbs}\)
2. \(R = 5 \text{ reps}\)
3. \[1RM = \frac{225 \times 36}{37 - 5} = \frac{8100}{32} = 253.125 \text{ lbs}\]

Visual Representation

The green portion of the bar represents the calculated 1RM (253.125 lbs) relative to 600 lbs.