To calculate your one-rep max using the Legion 1RM Calculator, review your training log and find the most weight you’ve lifted on an exercise for 3-to-6 reps, then plug the numbers into the calculator below. 

The Legion One-Rep Max Calculator

% of 1RM Weight Estimated reps
100% 1
95% 2
93% 3
90% 4
87% 5
85% 6
83% 7
80% 8
77% 9
75% 10
73% 11
70% 12

What Is A “One-Rep Max?”

A one-rep max (1RM) is the heaviest weight you can lift for a single repetition of a given exercise through a full range of motion with proper technique. 

Tracking your one-rep max using a 1-rep max calculator is beneficial because it allows you to monitor your strength progression. If you’re one-rep max is increasing, your strength training program is working, and you’re gaining muscle and strength. 

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How Do I Test My One-Rep Max?

Follow this 7-step process to do a repetition-max (or “rep-max”) test and calculate your estimated 1RM:

  1. Choose which exercise you’d like to test. For this example, let’s use the bench press
  2. Review your training log to find your most recent workout in which you performed the bench press. Note the weight you lifted and the number of repetitions you completed.
  3. Input the weight you lifted and the number of reps you did in the 1 rep max calculator above.
  4. Note 90% of your bench press one-rep max. You’re going to use this as your starting point to test your repetition maximum.
  5. Warm up thoroughly in your next bench press workout, then load the bar with 90% of your one-rep max. (If it isn’t already, rearrange your workout so the bench press is the first exercise you perform. Doing so ensures you get more accurate results.)
  6. Do as many reps as you can with 90% of your one-rep max, ending the set one rep shy of technical failure, the point at which your form begins to break down. (Training this close to failure is perfectly safe and effective. Don’t push beyond it, though, as doing so may increase your risk of injury.)
  7. Go back to the max rep calculator above and enter the numbers from your most recent bench press workout. 
  8. The calculator should now accurately estimate how much you can bench press for a single repetition

How Can I Improve My One-Rep Max?

You can improve your one-rep max in many ways. The simplest method is to follow a well-designed training program that emphasizes progressive overload, like Bigger Leaner Stronger or Thinner Leaner Stronger.

Beyond that, focus on the following:

  • Practice: The best way to get stronger at an exercise is to practice that exercise—you improve your squat strength by squatting, your deadlift by deadlifting, and so forth. Thus, if you want to improve your bench press but currently only bench once weekly, start benching twice per week.
  • Build muscle: As a new weightlifter, you’ll find most strength gains come from honing your technique. However, as you become more experienced (after 1-to-2 years of consistent weightlifting), building more muscle is one of the most effective ways to increase your one-rep max strength. If you want a program designed to help experienced weightlifters build muscle and get strong, check out my fitness book Beyond Bigger Leaner Stronger.
  • Train with heavy weights: You must regularly train with weights near your maximum to improve your one-rep max strength. A good guideline is to spend approximately 80% of your gym time training in the 4-to-6 rep range (85-to-90% of your one-rep max) and the remainder training in the 6-to-8 or 8-to-10 rep range (75-to-85% of your one-rep max).

FAQ #1: How do you calculate your 1-rep max?

Learning how to calculate one-rep max is easier than you might expect. A one-rep max (1RM) is the maximum amount of weight you can lift for a single rep of a given exercise. 

To easily calculate your one-rep max, review your training log and find the most weight you’ve lifted on an exercise for 3-to-6 reps. Then, plug the weight and reps into the Legion One-Rep Max Calculator above and calculate your one-rep max.

FAQ #2: How accurate is a one-rep max calculator?

A one-rep max calculator is accurate when using a weight that you lifted for around 5-to-8 repetitions. If a calculator uses an 8+ rep max to estimate your one-rep max, it will be significantly less accurate.

FAQ #3: What’s a “good” 1RM for the squat, bench, and deadlift?

A “good” one-rep max for the squat, bench, and deadlift depends on several factors, including your gender, body weight, and level of training experience. The best way to see how you stack up against other lifters is to use what are called strength standards—benchmarks for exercises based on your sex, body weight, and training experience.