1RM: One Rep Max Calculator

by Nader Qudimat
Updated June 11, 2023

When it comes to strength training, understanding your One Rep Max (1RM) is crucial.

This number represents the maximum amount of weight you can lift for one repetition of a given exercise.

It's not just a badge of honor, but a key data point that can guide your training program.

Use the calculator below to figure out how much weight you should use for your programs:

One Rep Max Calculators

Brzycki 1 Rep Max Calculator

The Brzycki formula is a popular choice for beginners and intermediate lifters.

It's simple and straightforward, making it a great starting point if you're new to 1RM calculation.

However, it tends to underestimate 1RM for higher rep ranges, so it's most accurate when used with a weight you can lift for 10 reps or fewer.

One Rep Max Calculator: Brzycki Formula

Results

One Rep Max:

Lander Formula

The Lander formula is another good option for beginners and intermediate lifters.

It's similar to the Brzycki formula but tends to be more accurate for higher rep ranges.

Lombardi Formula

The Lombardi formula is best suited for lifters who are focusing on powerlifting or other strength-based training.

It's based on the principle that your strength is proportional to the square of your mass, making it a good choice if you're training for strength rather than hypertrophy or endurance.

O'Conner Formula

The O'Conner formula is a versatile option that works well for a wide range of rep ranges.

It's a good choice if you're an intermediate or advanced lifter and you want a formula that can handle both low and high rep ranges.

Schwartz Formula

The Schwartz formula is designed specifically for powerlifters.

It takes into account your body weight as well as the weight you're lifting, making it a good choice if you're training for a powerlifting competition.

Wathan Formula

The Wathan formula is the most complex of the bunch, but it's also the most accurate for a wide range of rep ranges.

It's a good choice if you're an advanced lifter and you want the most accurate 1RM estimate possible.

Epley Formula

The Epley formula is a simple and widely used method for estimating one's one-repetition maximum (1RM).

It's particularly suitable for those focusing on strength training and powerlifting. The formula is straightforward and easy to use, making it a popular choice among both beginners and more experienced lifters. However, like all 1RM formulas, it's an estimation and actual max lifts may vary.

This formula is particularly useful for those who are new to lifting and want a quick and easy way to estimate their 1RM.

Mayhew Formula

The Mayhew formula is another method used to estimate one's one-repetition maximum (1RM).

This formula is often used in research settings due to its accuracy across a wide range of rep ranges.

It's a good choice for those who are performing lifts with higher repetitions and want a reliable estimate of their 1RM. 

1RM Calculator

All 1RM Calculators

Brzycki



Epley



Lander



Lombardi



Mayhew et al.



O'Conner et al.



Wathan



The Importance of 1RM

Knowing your 1RM is important for several reasons.

It allows you to track your progress over time, set realistic goals, and design an effective workout program. It's also essential for determining the appropriate weight to use in various strength training programs, many of which are based on percentages of your 1RM.

Different Methods for Calculating 1RM

There are several methods you can use to estimate your 1RM. One of the most popular is the Brzycki Equation, which is based on the number of repetitions you can perform to failure with a given weight.

Other methods include the Lander, Lombardi, O'Conner, Schwartz, and Wathan formulas, each of which uses a slightly different calculation to estimate 1RM.

Using a 1RM Calculator

A 1RM calculator is a tool that can help you estimate your 1RM without having to test it directly.

You simply input the amount of weight you can lift and the number of repetitions you can perform to failure, and the calculator will estimate your 1RM based on one of the aforementioned formulas.

The Role of 1RM in Training Programs

Many strength training programs are based on percentages of your 1RM. For example, you might be instructed to lift 75% of your 1RM for a certain number of sets and repetitions.

Knowing your 1RM allows you to determine exactly how much weight to use for these workouts.

Safety Considerations

While knowing your 1RM can be very useful, it's important to remember that testing your 1RM can be risky, especially without proper form and supervision.

That's why many people prefer to estimate their 1RM using one of the methods described above.

FAQ

  • What is a 1RM? A 1RM, or one rep max, is the maximum amount of weight you can lift for one repetition of a given exercise.

  • Why is knowing my 1RM important? Knowing your 1RM is important for tracking your progress, setting realistic goals, and designing an effective workout program. Many strength training programs are based on percentages of your 1RM.

  • How can I calculate my 1RM? You can calculate your 1RM by testing it directly or estimating it using a 1RM calculator. The calculator uses a formula based on the amount of weight you can lift and the number of repetitions you can perform to failure.

  • Is it safe to test my 1RM? Testing your 1RM can be risky, especially without proper form and supervision. That's why many people prefer to estimate their 1RM using a calculator.

  • Can I use my 1RM to determine how much weight to use in my workouts? Yes, many strength training programs are based on percentages of your 1RM. Knowing your 1RM can help determinate how much weight you need to use.

Bottom Line

Understanding your 1RM is a key part of strength training.

Whether you choose to test it directly or estimate it using a calculator, knowing this number can help you track your progress, set goals, and design an effective workout program.

Just remember to always prioritize safety and proper form, especially when lifting heavy weights.

by Nader Qudimat

Forged by iron and cold steel, I'm Nader, a mid-30s natural bodybuilder. Once a 100lb skinny guy, I've transformed into a 200lb muscular athlete with over 15 years of lifting experience. Today, I leverage my transformation and extensive experience to guide countless individuals on their fitness journeys.

Click here to check out my 12 year transformation: Natural 12 Year Transformation

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