Brzycki Equation Calculator - Calculator Academy

Enter the weight lifted (in lb, kg, or g) and the number of reps performed into the Calculator. The calculator will evaluate the estimated 1RM using the Brzycki Equation.

Safety note: This calculator provides an estimate only and may vary by individual. Don’t attempt a true 1RM based solely on this number—use appropriate warm-ups, safeties/spotters, and stop if you feel pain, dizziness, or unusual symptoms. If you’re new to lifting, returning from injury, pregnant, or have a medical condition, consider guidance from a qualified coach or clinician.

1RM from Brzycki Equation Formula

1RM = w / [(1.0278)-(.0278*r)]

Variables:

1RM is the estimated one-repetition maximum (same unit as w, e.g., lb or kg)
w is the weight lifted for r reps (same unit as 1RM)
r is the number of reps performed in the exercise

Note: The Brzycki equation is an estimate and is generally considered most accurate when r is in lower rep ranges (commonly around 1–10 reps). Accuracy tends to decrease as reps get much higher.

References / further reading

For background on the Brzycki 1RM prediction equation and recommended rep ranges, consult the original Brzycki publication and reputable strength & conditioning references (for example, NSCA materials) for guidance on testing and programming.

How to Calculate 1RM from Brzycki Equation?

The following steps outline how to calculate the 1RM from Brzycki Equation.

First, determine the weight lifted for the set (w).
Next, determine the number of reps performed in that set (r).
Next, gather the formula from above = 1RM = w / [(1.0278)-(.0278*r)].
Finally, calculate the estimated 1RM from the Brzycki Equation.
After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem :

Use the following variables as an example problem to test your knowledge.

weight lifted (lb) = 300

number of reps performed in the exercise = 10

Frequently Asked Questions

What is 1RM and why is it important?

1RM stands for one-repetition maximum, which is the maximum amount of weight one can lift in a single repetition for a given exercise. It's important because it's a standard measure of the maximum strength of an individual and is used to guide the intensity of weight training programs.

How often should I test my 1RM?

Testing your 1RM too frequently can be taxing on your body and may hinder your progress due to recovery needs. It's generally recommended to test your 1RM every 3-6 months, depending on your training program and goals.

Can I use the Brzycki Equation for any exercise?

While the Brzycki Equation can be applied to many resistance exercises, it tends to be most useful for common compound lifts like the squat, bench press, and deadlift. For isolation exercises, the equation may not provide as accurate results due to differences in technique and muscle involvement.

What rep range is the Brzycki Equation best for?

It is generally considered most accurate for lower rep ranges (commonly around 1–10 reps). Using very high-rep sets can reduce accuracy because fatigue and endurance become a larger factor than maximal strength.

Is it safe to calculate and attempt my 1RM?

Calculating your 1RM using equations like the Brzycki formula can provide an estimate without physically lifting the maximum weight, which is safer. However, if you choose to physically attempt your 1RM, it's crucial to do so with proper form, adequate warm-up, and preferably under the supervision of a trained professional to minimize the risk of injury.