One-Rep Max Calculator

Created by Michael Darcy
Reviewed by Dominik Czernia, PhD candidate and Alexa Ruiz
Last updated: Apr 06, 2022

One of the most popular phrases used in sports is "push your limits" - and our one-rep max calculator is here to help you find out what they are. If you're wondering why it's worth knowing your maximum lift, how to calculate your one-rep max, and how it's used to measure your strength with the Wilks score - read on!

What is one rep max?

Single repetition maximum (also abbreviated as 1RM) is one way of assessing your strength and represents the heaviest weight you can lift. You could compare it to what VO2 max is for runners.

It's possible to test one-rep max in practice by simply increasing the load on the barbell; however, this method isn't recommended for everyone, especially novices with little experience due to the risk of injury. Luckily, if you can do a certain amount of repetitions with a lighter weight, it's possible to predict your maximum lift.

Why is knowing your maximum lift useful?

The result from the one-rep max calculator can be used to track your progress or to compare yourself to others, for example, with the Wilks score. This is a pretty standard measure of your weightlifting abilities that can help you tell who's a better lifter regardless of their sex or weight.

Tracking your one-rep maximum may also indicate that there's something wrong with your technique or particular muscle group if the progress is different than expected. Additionally, the single repetition maximum percentage is used in some exercise plans, for example, in powerlifting or CrossFit Workouts of the Day (usually referred to as WODs).

Epley formula: How to calculate one-rep max?

Since there are many factors affecting body performance, estimating your single repetition maximum isn't simple. There are many formulae, some giving more accurate results than the others, but all of them should be treated with a grain of salt. The one-rep max calculator uses two methods:

  • The Epley formula

This one rep max formula, alongside the Brzycki formula, has been around since the end of the 20th century and has proven itself to be quite accurate. The equation is as follows:

1RM = weight * (1 + (number of reps/ 30)).

It's meant to work for any lift, but you might want to adjust it yourself - your squat max will most likely be higher than your bench press maximum.

  • The NSCA exercise specific coefficients

The National Strength And Conditioning Association took a step further and prepared a list of coefficients to multiply by the weight, depending on the number of repetitions. They accommodate the fact that your maximum lift depends on its type as each of them focuses on different muscle groups. The NSCA factors are:

Number of repetitions Squat Deadlift Bench press
1 1.00 1.00 1.00
2 1.0475 1.065 1.035
3 1.13 1.13 1.08
4 1.1575 1.147 1.115
5 1.2 1.164 1.15
6 1.242 1.181 1.18
7 1.284 1.198 1.22
8 1.326 1.22 1.255
9 1.368 1.232 1.29
10 1.41 1.24 1.325

Regardless of how you find your rep max, keep in mind that the fewer the repetitions, the more accurate the result. For example, if you want to test your squat maximum, it's better if you calculate your one-rep max using the weight used in a set of three rather than eight.

What percentage of my one rep max should I lift?

Knowing your limits may help program your workouts, but the percentage you should use depends on your goal. Generally, the areas of use are:

  • Explosive power: 50% of 1RM. This term may be unfamiliar for many people, but it's pretty simple. Think about an explosion - it happens rapidly and releases an enormous amount of energy. Therefore, explosive power in sports relates to your ability to exert your maximum strength in minimal time. Your muscles will learn how to generate power without becoming too large and slow.
  • Endurance: 70% of 1RM. Endurance is the ability of a muscle (group) to continue contracting over an extended time period. To put it simply, the greater your endurance, the longer you can keep moving. This type of training uses the greatest number of repetitions and also increases your metabolic rate for a couple of hours.
  • Hypertrophy: 80% of 1RM. Hypertrophy is a sophisticated way to speak about building muscle mass. If you're a bodybuilder, you probably aim for this percentage.
  • Power: 90% of 1RM. This type of training is about lifting heavy weights at speed to exert maximal force quickly, but not to be confused with explosive movements.
  • Strength: 95% of 1 RM. This is the fastest route to increase your one-rep max, but you shouldn't overdo it. Keep the repetitions within range 1 - 3, and ideally, you should have someone to watch over you (a so-called spotter). There's no pride in setting a new bench press max if the barbell crushes your vital organs.

Our tool also provides the one rep max chart, so you can find the percentage that's appropriate for your goal without any additional calculations.

How to increase one-rep max?

Plenty of us start exercising to become a better version of ourselves, but apart from how to increase one-rep max, another question arises: how to do it in a healthy way? Below you will find the most crucial factors that may affect your performance:

  • Regular training is the most obvious way of becoming fitter. You want to work hard, but still keep it smart. Now that you know the answer to "what percentage of my one-rep max should I lift?", reaching your goal should be easier. However, if unsure, we always recommend consulting a professional as safety should always come first.
  • This may be a bit of a surprise, but proper rest is just as important. You won't get the results you want if you place too much strain on your body; your muscles grow stronger when you regenerate after exercise. Getting the right amount of sleep is especially important. Knowing your one-rep max won't help if your body's too overworked to get to that desired percentage.
  • Food is basically your fuel, so you should take care of proper nutrition. You don't necessarily need to calculate your macros if you're just a casual gym-goer, but knowing your recommended calorie intake may be helpful. If that's too much effort, try to at least consume enough protein as they play a vital role in building lean muscle mass and may speed up the recovery.
  • Drinking alcohol on the contrary, may have a negative impact on your athletic performance. Not only does it dehydrate you, it may lead to weight gain, interfere with recovery and affect your growth hormone. It doesn't mean that you have to remove your favorite beverage entirely from your life, but limiting the consumed alcohol units may be beneficial.


How to test your one-rep max?

You can test it by increasing the load on the barbell until you can't lift it - then, the last successful attempt determines your 1RM. Alternatively, find a weight that you can lift 2-6 times and calculate your predicted one-rep max, for example, using the Epley formula.

How often should you do one-rep max?

Generally, not more than once every few weeks. It should be even less frequent as your fitness level increases - the heavier the weight, the more rest your body needs between the tests.

How much should your one-rep max be?

There's no set value you should compare yourself to. We all have different body types, and your performance also depends on other factors such as sleep, nutrition, or even the weather. Aim to be better than your past self!

How to calculate one-rep max for deadlift?

To find your max deadlift, find the maximum weight you can lift 1-10 times and multiply it by an appropriate NSCA coefficient. They are specified for different lifts, so the results may be more accurate than if you used a general 1RM formula such as Epley or Brzycki.

Michael Darcy
Not specified
One-repetition maximum
Percentage of 1RM
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