What is one rep max (1RM)?

One rep max (1RM) is the maximum weight you can lift for a single repetition of an exercise. It's a measure of strength and is used to determine training loads for different training goals. For example, if your bench press 1RM is 200 pounds, you might train with 80% of that (160 pounds) for strength training.

Which 1RM formula is most accurate?

The Epley formula is often considered one of the most accurate for general use. The Brzycki formula is also widely used and tends to be more conservative. The Lombardi formula works well for power-based movements. Different formulas may give slightly different results, so comparing multiple formulas can give you a better range estimate.

How many reps should I use to calculate 1RM?

For best accuracy, use a weight you can lift between 1 and 10 times. The closer you are to your actual max (fewer reps), the more accurate the estimate. Using 3-5 reps is often ideal as it balances accuracy with safety. Avoid using very high rep counts (15+) as accuracy decreases significantly.

Should I actually test my 1RM?

Testing your actual 1RM can be risky and should only be done with proper form, warm-up, and preferably with a spotter. Using a calculator based on submaximal lifts is safer and still provides useful estimates for training. If you do test your 1RM, do so gradually and never attempt it without proper preparation.

How do I use my 1RM for training?

Once you know your 1RM, you can calculate training percentages: 90-100% for strength/power (1-3 reps), 80-90% for strength (4-6 reps), 70-80% for hypertrophy (8-12 reps), and 50-70% for endurance (12+ reps). This helps you train at the right intensity for your goals.

One Rep Max Calculator

Estimate the maximum weight you can lift for a single repetition based on the number of repetitions you can perform with a certain weight. For the most accurate estimate, use a weight that you can lift between 1 and 10 times.

Weight Lifted (pounds)

Repeated (1-10 times)

1RM Estimation Formula

Desired Unit

What is One Rep Max?

A "one rep max" (one-repetition maximum) is the maximum weight a person can lift for one complete repetition of a specific exercise while maintaining proper form. It is a measure that is commonly used in weightlifting competitions since it represents the peak force that a person's muscles can generate in an all-out effort.

A person's one rep max typically differs based on the exercise, whether it be a bench press, squat, deadlift, overhead press, or whatever other exercise is being performed. Thus, it is important to measure a one rep max for a given exercise rather than applying a one rep max in one exercise to other exercises.

Why One Rep Max is Important

Knowing your one rep max (1RM) is valuable because it provides a quantitative measure (or estimate) of your maximal strength for a given exercise, which enables you to design a workout program and train accordingly based on your goals.

For example, you can use your 1RM to manage your targeted training intensity. This enables you to design a workout program that is challenging enough to promote strength gain while also ensuring proper technique and safety.

Since it provides a quantitative measure, knowing your 1RM also allows you to track your strength progress over time and set goals for improvement. Without a quantitative measure, it can be difficult to motivate ourselves to train. Seeing improvement in your 1RM can help motivate you to train, or if you don't see improvement, you can use your 1RM to adjust your workout program to help you achieve your desired strength gains.

How to Measure One Rep Max

The two primary methods for measuring one rep max are direct measurement by performing a strength test for a given exercise and using estimation methods. There are advantages and disadvantages to using either method.

Direct Measurement

Directly measuring one rep max involves progressively increasing the weight as you perform a specific exercise. As you increase the weight, taking breaks between each trial, the number of repetitions of the exercise you can perform should continue to decrease until your muscles reach failure and you can only perform one repetition of the exercise with proper form.

Safety Warning: This method of measuring one rep max can be dangerous, and it is important to only attempt using direct measurement for exercises you are experienced in performing, ideally with the help of a spotter.

Steps for direct measurement:

Warm up: Begin by warming up the muscle groups you will be using.
Find a spotter: Having a spotter helps you push your limits safely.
Start with a comfortable weight: The weight should be one you can lift for ~5-10 reps.
Rest and recover: Between each set, rest 2-5 minutes.
Progressively increase weight: Continue increasing weight until you can only do one repetition with good form.
Record your estimated 1RM: Note your 1RM for future reference.

Advantages: Straightforward and more accurate than estimation methods.

Disadvantages: Higher risk of injury and time consuming due to required rest periods.

Estimation Methods

There are various formulas used to estimate one rep max. This calculator provides calculations for the Epley, Brzycki, and Lombardi formulas:

Epley Formula

1RM = Weight Lifted × (1 + Repetitions/30)

Brzycki Formula

1RM = Weight Lifted × 36/(37 – Repetitions)

Lombardi Formula

1RM = Weight Lifted × (Repetitions)^0.10

Steps for estimation:

Select a challenging but safe weight: Pick a weight you can lift for 3-10 reps.
Repeat until failure: Keep lifting until you reach failure (cannot complete another rep with proper form).
Record the weight and number of reps: Plug these values into the calculator.

Advantages: Lower risk of injury, time efficient, and more accessible to beginners.

Disadvantages: Less accurate than direct measurement, especially for beginners. Usually estimates are within 10% of actual 1RM, though can vary more.

How to Use One Rep Max

Once you have measured your one rep max, you can use it to help manage your targeted training intensity based on your strength goals. In general, lifting at a certain percentage of your one rep max promotes different things:

50-60% of 1RM for 3-5 reps (4-6 sets): Lifting a lower number of reps at a lighter weight can help with promoting explosive power. Keep breaks between sets shorter.

~70% of 1RM for 10-15 reps (4-6 sets): Lifting at around 70% of your 1RM for more repetitions helps promote muscle endurance.

70-80% of 1RM for 7-12 reps (3-5 sets): Lifting in this range can help with muscle growth.

80-100% of 1RM for 1-3 reps (3-4 sets): Lifting in this range promotes a combination of muscle growth, power, and overall strength. Use a spotter whenever possible.

How to Improve One Rep Max

The following are some general ways to improve your one rep max, primarily useful for beginners:

Prioritize Safety

Prioritize proper form: Form can almost always be improved. Be conscious and dedicated to learning and maintaining proper form, especially when near your limits.
Get a spotter: Whenever possible, and especially when attempting heavier weights, train with a spotter to help prevent injury.

Train Consistently

Building strength requires consistency. When trying to improve one rep max, you should try to train at 85%-100% of your one rep max. However, training at 70% is still better than not training. Remember that rest is also an important part of gaining strength.

Rest

It is definitely possible to overtrain. Muscles need time to recover and grow, and pushing them to their limits constantly can negatively impact your strength goals, especially in the case of injury.

Vary Your Workouts

In the beginning, just repeatedly performing the exercise you want to improve will likely result in strength gains. However, eventually it will likely lead to a plateau. Try different types of sets:

Supersets: Perform multiple different exercises without rest between sets.
Compound sets: Similar to supersets but work the same muscle groups.
Pyramid sets: Start with lower weight and many reps, then increase weight while decreasing repetitions.

Train your surrounding muscles: Training supportive muscles reduces risk of injury and may help with overall strength, especially if you're at a plateau.

Disclaimer

Always consult with a qualified fitness professional or healthcare provider before engaging in maximal strength testing or starting a new exercise program. Safety should be the top priority when assessing and training for maximal strength.