One-Rep Max Calculator – Calculate Your 1RM

Calculate your one-rep max using the reps and weight you lifted.

Calculated One-Rep Max:

Calculated using the Brzycki formula [1]
Learn how we calculated this below

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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 as many training adaptations require the utilization of a specific percentage of your 1RM to most effectively achieve desired results. For example:

  • Power: 75-90% 1RM
  • Strength: >= 85% 1RM
  • Hypertrophy: 67-85% 1RM
  • Endurance: <= 67% 1RM

Strength training burns calories while you exercise and also builds lean muscle mass. The lean muscle gained during these workouts will increase your resting metabolic rate and allow you to burn more calories 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 you are able to perform at a lighter weight.

One reason for using this calculation instead of just attempting to lift a heavy weight is to minimize your risk of injury. Especially for beginners, attempting a true 1RM test by simply “guessing” your one-rep max can place an unnecessary amount of stress and load on muscles, tendons, ligaments, and bones, increasing your risk of injury.

For this calculation:

1RM = weight lifted × 36 / 37 – reps

Max Reps

A helpful 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.

Especially for novice lifters, research has shown that individuals performing weight lifting sets with low reps using a heavy weight versus high reps using lighter weights have similar muscle growth.[4] By performing max reps with a lighter weight, you can determine your one-rep max while decreasing the risk of injury, and utilize that information to help determine weights to be used in your future training sets.

For trained athletes looking for maximum muscle adaptation, research has also shown that using heavier weights may be necessary and efficient for amplifying strength gains.[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. One study in particular found that formulas to calculate one-rep maxes are most accurate for bench press, as compared to deadlifts or squats.[6]


One of the best weight-lifting exercises to determine lower body strength is the squat. This movement 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 if performed incorrectly, determining a one-rep max using a formula is a much safer way than trying to perform a true 1RM test and risk failure or injury. The calculations for a one-rep max for squats are slightly less accurate as compared to bench press, but will still provide valuable data to inform your future training weights.

Max Deadlift

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

A calculated one-rep max is very important for deadlifts since proper form rather than heavier weight is most important when you first start doing this exercise. This will help to avoid injury and to efficiently target the appropriate muscles rather than promote compensation (utilization of improper muscles) and increase your risk of injury.

Once determined, you can then lift a percentage of your one-rep max until you perfect the technique and gradually increase the weight you are using. It can be noted that the formulas for one-rep max have been found to underestimate the deadlift one-rep max, which is quite alright for the novice lifter, where form should continue to be the main focus as weight is progressed.

A calculated 1RM is a good starting point when beginning a strength training program. Utilize the help of a trainer if necessary – and don’t forget that you can always begin to learn proper technique with an empty barbell or even a PVC pipe!


  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.