One-Rep Max Calculator – Calculate Your 1RM

Calculate your one-rep max based on the reps and weight you lifted today

Calculated One-Rep Max:

Calculated using the Brzycki formula [1]

How to Calculate Your One-Rep Max

In a weight lifting program, every routine consists of a certain amount of reps, sets, and weight that you lift for each exercise. One of the hardest things for beginners is figuring out how much weight they should be lifting for any given exercise.

A good starting point is to determine your one-rep max, or 1RM. From there, you can adjust your reps and sets in your strength training routine based on a percentage of your one-rep max.

Determining your one-rep max is important for any weightlifting program. Strength training burns calories while working out and also builds lean muscle mass. The lean muscle gained during these workouts will increase your resting metabolic rate and allow you to burn calories more even at rest.

It should come as no surprise that strength training has been shown to increase lean muscle mass in several studies, leading to increases in resting metabolic rate.[2][3]

One-Rep Max Formula

One way to estimate your one-rep max is to use the Brzycki formula. In this calculation, the one-rep max is based on the total number of reps lifted while using a lighter weight.

The reason for using this calculation instead of just attempting to lift a heavy weight is to avoid injuries. Attempting a lift with heavy weight by simply trying to “guess” your one-rep max can place an unsafe amount of stress and load on muscles, tendons, ligaments, and bones.

For this calculation:

1RM = weight lifted × 3637 – reps

Max Reps

A strategy to determine your one-rep max is choosing a lighter weight and performing as many reps as you can with proper form until you fatigue.

Studies have found that individuals performing weight lifting sets with low reps using a heavy weight versus high reps using lighter weights have similar muscle growth.[4]

However, for trained athletes looking for maximum muscle hypertrophy, using heavier weights is still the best option for maximizing strength adaptations.[5] By performing max reps with a lighter weight you can determine your one-rep max without an increased risk for injury.

1RM Weight Percentage Table

Weight percentage of one-rep max for max repetitions
Percent of 1RM Max Reps
100% 1RM
95% 2RM
93% 3RM
90% 4RM
87% 5RM
85% 6RM
83% 7RM
80% 8RM
77% 9RM
75% 10RM
73% 11RM
70% 12RM
strength training athlete doing a one-rep max on the bench press

Bench Press

The bench press is the gold standard exercise to assess the strength of the chest, or pectoral muscles. This is also a good lift to help measure the strength of the shoulders and triceps.

Using <10 reps at about 85% of the one-rep max appears to be the best way to estimate the one-rep max. Studies have found that formulas to calculate one-rep max are most accurate for bench press.[6]


One of the best weight lifting moves to determine lower body strength is the squat. This move targets the glutes, hamstrings, quads, and calves while also requiring core stabilization.

Since squats can place a large amount of strain on the lower back, determining the one-rep max using a formula is a much safer way than trying to lift a heavier weight than one can handle. The calculations for one-rep max are slightly less accurate for squats as compared to bench press.

Max Deadlift

The deadlift is a great strength training move that targets several muscle groups at once. Deadlifts strengthen the glutes, hamstrings, and quads. Plus, you’re activating muscles in the upper back, core, and deltoids during the movement.

Calculating a one-rep max is very important for deadlifts since you really need to focus on form, and not so much on using a heavy weight, when you first start doing this exercise. This is important to avoid injury.

You can then lift a percentage of your one-rep max until you perfect the technique and gradually increase the weight you are using. The formulas for one-rep max have been found to underestimate the deadlift one-rep max.

However this is still a good starting point when beginning a strength training program.


  1. Brzycki, Matt, Strength Testing – Predicting a One-Rep Max from Reps-to-Fatigue, The Journal of Physical Education, Recreation & Dance, 1993, 64.1, 88-90.
  2. Pratley, R., Nicklas, B., Rubin, M., Miller, J., Smith, A., Smith, M., et. al., Strength training increases resting metabolic rate and norepinephrine levels in healthy 50-to 65-yr-old men, Journal of Applied Physiology, 1994, 76(1), 133-137.
  3. Campbell, W. W., Crim, M. C., Young, V. R., & Evans, W. J., Increased energy requirements and changes in body composition with resistance training in older adults, The American Journal of Clinical Nutrition, 1994, 60(2), 167-175.
  4. Brunelli, D. T., Finardi, E. A., Bonfante, I. L., Gáspari, A. F., Sardeli, A. V., Souza, T. M., et. al., Acute low-compared to high-load resistance training to failure results in greater energy expenditure during exercise in healthy young men, PloS One, 2019, 14(11), e0224801.
  5. Schoenfeld, Brad J.; Peterson, Mark D.; Ogborn, Dan; Contreras, Bret; Sonmez, Gul T., Effects of Low- vs. High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men, The Journal of Strength & Conditioning Research, October 2015, 29(10), 2954-2963.
  6. LeSuer, D. A., McCormick, J. H., Mayhew, J. L., Wasserstein, R. L., & Arnold, M. D., The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift, Journal of Strength and Conditioning Research, 1997, 11, 211-213.