Squat 1 Rep Max (1RM) Calculator: With 7 Formulas

Our squat one-rep max calculator is specifically designed to make use of the 7 most suitable 1RM formula for the squat exercise itself - all of which are further outlined and explained below.

In order to get the most out of this calculator, you will need to first perform a test set with the maximum amount of weight you can squat for more than one repetition (for example 225 lbs x 4 reps).

Once the test set is performed, simply plug in the weight squatted and the number of repetitions you lifted said weight for. In addition, you will also need to pick which one-rep max formula the calculator will use.

For the sake of accuracy, limit your repetition input to 12.

For a more detailed coverage on what each 1RM formula entails, as well as which one is more suitable for you, read on.

Squat 1RM Formulas

The following one-repetition maximum formulae feature two variables: 

1. R or repetitions refers to the number of repetitions performed in the set.
2. W or weight refers to the amount of weight lifted with each repetition.

Brzycki Formula

The Brzycki formula is one of the most popular equations used for calculating a one-rep max, and is considered to be highly accurate for the back squat in particular.

It was formulated on a relatively diverse sample population and is applicable to all types of resistance exercises and individuals.

Equation:

1RM = W x (36 / (37 – R))

Epley Formula

The Epley formula is considered to be on-par with the Brzycki formula in terms of accuracy of squat 1RM estimation. 

In contrast to other formulas, Epley's formula exhibits an inverse coefficient association with the variable R, representing the number of repetitions executed during the test set.

Consequently, the Epley formula may not provide as accurate estimations for weightlifters who have reached advanced levels of development.

Equation:

1RM = W x (1 + 0.0333R)

O’Conner et al. Formula

In comparison to other modern formulas, the O'Connor formula takes a different approach to the 1RM estimation by assigning a lower significance to volume.

It employs a coefficient value of 0.025, which leads to a bias towards high volume sets. 

As a consequence, when a test set with a high volume is input, the formula yields a 1RM value that is considerably higher.

Equation:

1RM = W x (1 + (0.025 x R))

Lombardi Formula

The Lombardi formula assumes a non-linear relationship between repetitions (R) and weight lifted (W).

This means that it is less accurate for weightlifters with significant muscular endurance, but otherwise perfectly applicable for other types of lifters performing the squat.

Equation:

1RM = W x (R ^ 0.1)

Lander Formula

The Lander formula is particularly unique among 1RM formulae because of its attempt to include the lifter’s own bodyweight as part of the calculation. 

This addition makes the Lander formula especially applicable to weightlifters who participate in sports that feature weight class divisions, such as powerlifters or martial artists.

Equation:

1RM = (100W) / (101.3 – 2.67123R)

Mayhew et al. Formula

The Mayhew et al. formula is another popular 1RM formula with a wide range of applicability, meaning that it can be used for a variety of different exercises and types of lifters.

Equation:

1RM = (W x (0.025 x R + 0.75))

Berger’s Table/Formula

Regarded as one of the simplest methods for calculating the one-repetition maximum (1RM), the Berger formula stands out for its straightforwardness. It involves using a fixed constant to estimate the maximum load based solely on the number of repetitions performed.

Equation:

1RM = (W x R x 0.033) + W

What’s the Best 1RM Formula for Squats?

Although most one-repetition maximum formulas are perfectly applicable to any exercise, reviews conducted by researchers have found that it is in fact the two most popular modern equations that are best suited for the squat - that is to say, the Brzycki and Epley formulas.

These formulas are most accurate when calculated with the range of 2-5 repetitions in the test set, as is outlined in a report released by Southern Illinois University Carbondale;

“the Epley and Brzycki equations accurately predicted a back squat 1RM to within 2.7 and 3.1kg from a 5RM and a 3RM test.”

Of course, given the limitations of the formula used and individual physiological variation, it is best to average out the returned 1RM from both of these formulas (alongside others) in order to get a more accurate estimation.

What is a One-Repetition Maximum, and Why is it Important?

A “one-repetition maximum” or simply 1RM is the maximum amount of weight a lifter can move during a single repetition of an exercise at the limit of their physical capabilities.

It is primarily derived from inputting a lighter “test” set into a formula or calculator, but may also be identified manually by actually lifting as much weight as is safely possible.

The Importance of One-Rep Maxes

1RMs are used for a variety of tracking and programming purposes, but are primarily estimated so as to create set/repetition schemes within resistance training programs. 

They may also be used for plotting progression schemes, identifying whether the lifter’s progress is sufficient for their needs and for estimating their comparative capabilities with their peers.

What is a 1RM Formula?

Simply put, a one-rep max formula is a mathematical calculation that takes the lifter’s testing set (weight and repetitions), and outputs an estimated 1RM.

This allows the lifter to identify the maximum weight they can lift without actually going through the exertion and risks of doing so. 

How Do You Calculate a One-Rep Max?

While clinical studies have come up with a number of novel ways to estimate maximal load potential (such as bodily circumference or sub-maximal velocity measurement), the simplest and most accessible way is to calculate it through an equation.

This can be achieved by inputting repetitions and weight into our calculator, or by doing the math yourself. 

However, these calculations are somewhat limited by the accuracy of the formula used, and as such some lifters find that the most accurate way of identifying a squat 1RM is actually through manual testing - although doing so comes with its own inherent risks and problems.

Manual 1RM Testing

Manually testing a squat 1RM is quite literally just performing the squat for a maximum effort repetition.

While this is the most sound and accurate method of identifying your current one-rep max, it can be quite taxing and greatly increases the risk of injury. 

Unless you are an advanced weightlifter with a deep understanding of squat execution and have a spotter present, it is safer to stick with formulas and calculators.

Doing the Math Yourself

If you prefer to forego the calculator and do the calculations yourself, simply input the data from your test set into any of the given formulas above. 

Keep in mind that the variable R is the number of repetitions performed within the testing set, and the variable W refers to the amount of weight lifted per repetition, not in totality of the set.

This means that a set of 5 repetitions of 100 pounds will be input as R=5 and W=100.

How to Use a Squat 1RM for Training Optimization

Odds are, if you’re using this one-rep max calculator, you already know what to do with a 1RM. 

But if you don’t, the following are a few suggestions that can help optimize your training.

For Establishing Sets and Volume

Generally, the amount of weight and volume performed in a set is assigned by a percentage of your one-rep max. The specific percentage and volume will depend on the goals of the training program, but are largely predicated on the actual 1RM value itself.

For maximum hypertrophy, a training weight and volume of 60-80% of your 1RM for 8-12 repetitions is ideal. 

For strength development, approximately 80-100% for 1-5 repetitions per set is best. 

For muscular endurance, lifting below 60% of your 1RM for over 15 repetitions per set is the usual route taken.

As an example: if the goal is hypertrophy, a set of 8 repetitions of 80 pounds (36 kilograms) can be performed out of a 100 pound (45 kilograms) one-repetition maximum.

For Plotting and Tracking Strength Progression

Estimating your 1RM can allow you to plot out how long it may take to reach a heavier 1RM in the future. This is vital for long-term programming, as it allows lifters to designate periodization phases and to structure deload periods as needed.

Furthermore, a previous 1RM can be used to track the rate at which the lifter is developing in terms of strength, as it will show how long it took to build up the strength necessary to perform their current one-rep maximum.

This can be retroactively used to find problems in recovery, diet or programming.

For Benchmarking Strength “Level” by 1RM and Body Weight

Although a rough aggregate at best, lifters may compare their current 1RM against the average of their peers in weight, gender and age. This can help provide a baseline with which they may base their training methodologies and approaches on.

A good example of this is a male individual of 180 pounds being classified as an “advanced” weightlifter because their squat 1RM is over 380 pounds (172 kilograms) - or otherwise being stronger than 95% of their peers. 

Having such information can help the lifter pick a program that is more appropriate for someone of their training experience, as it would be distinct from an individual who has just begun performing resistance training - even if the two are identical in terms of gross weight, gender and age.

How Accurate is Your Squat One-Rep Max?

While the majority of one-rep max formulas are relatively correct, it is important to keep in mind that several factors relating to individual physiology and the limitations of math can skew the accuracy of their results somewhat.

Physiological Differences Between Lifters

No two lifters are physiologically the same - be it differences in muscle fiber composition, bodily leverages or even neurological adaptation. 

Such differences between individuals means that the sample population with which the 1RM formulas are based will be quite different from yourself, and as such can mean that the accuracy of said formulas may not correctly reflect your own physical capabilities.

Mathematical Limitations of Accuracy

Apart from physiological variation, the math employed in each formula can also lead to relative inaccuracies.

The limitations of the study’s data set, the personal preference of the research team and even assumed correlation between volume and resistance are major factors that can affect formulaic accuracy.

Bottom Line - Is Your Squat 1RM Correct?

For most intents and purposes? Yes - the one-rep maximum derived from our calculator or from the formulas above are relatively correct.

However, there is a small margin of error, and as such it is important to keep in mind that 1RM calculators output an estimate, rather than an undeniable fact.

It is entirely possible that your squat will be slightly stronger or weaker than what is displayed.

A Few Reminders on 1RM Testing and Squats

Regardless of whether you’ve chosen to calculate your 1RM or manually test it out yourself, remember that there are drawbacks to both approaches - especially manual testing.

Although testing out a squat 1RM is less risky than doing so with the bench press, it is nonetheless still a maximal effort exertion and comes with a significant risk of injury.

Ensure that you are cleared by a medical professional before attempting a one-rep max, and that you have an experienced spotter present to help.

References

1. Amarante do Nascimento, Matheus & Cyrino, Edilson & Nakamura, Fabio & Romanzini, Marcelo & Pianca, Humberto & Queiroga, Marcos. (2007). Validation of the Brzycki equation for the estimation of 1-RM in the bench press. Revista Brasileira de Medicina do Esporte. 13. 40e-42e.

2. DiStasio, Thomas J. "Validation of the Brzycki and Epley Equations for the 1 Repetition Maximum Back Squat Test in Division I College Football Players." ( Jan 2014).

3. Schoenfeld BJ, Grgic J, Van Every DW, Plotkin DL. Loading Recommendations for Muscle Strength, Hypertrophy, and Local Endurance: A Re-Examination of the Repetition Continuum. Sports (Basel). 2021 Feb 22;9(2):32. doi: 10.3390/sports9020032. PMID: 33671664; PMCID: PMC7927075.