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.

Exercise

Weight Lifted

lbs

Repetitions

reps

Awaiting Inputs

Enter your weight lifted and the number of repetitions completed to estimate your One Rep Max (1RM) and view your intensity breakdown.

A "one rep max" (one-repetition maximum or 1RM) 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.

How to use this calculator to save (and improve) your 1RM

After using the calculator to calculate your 1RM, there will be a save button in the result section. Click the save button to save your 1RM for future reference. You can then look back at your previous 1RM for various exercises in your dashboard to gauge your progress. The following sections provide detail on the 1RM calculation as well as methods for working toward improving your 1RM.

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.

Direct Measurement

Directly measuring one rep max involves progressively increasing the weight as you perform a specific exercise until your muscles reach failure and you can only perform one repetition.

Straightforward: Keep lifting more weight until you can only do one proper repetition.
More accurate: Direct measurement is inherently the most accurate indicator of your limit.
Higher risk of injury: Pushing muscles to absolute failure carries a higher risk.
Time consuming: Requires ample rest (3-5 mins) between attempts.

Estimation Methods

Using formulas (like Epley or Brzycki) to estimate 1RM by performing a set of 3-10 repetitions to failure at a sub-maximal weight.

Lower risk of injury: Lifting lower weights for more reps is much safer.
Time efficient & Accessible: Easier to integrate into a standard workout routine.
Less accurate: Mathematical estimates deviate based on muscle fiber composition and experience level.

How to use one rep max (Targeted Intensity)

Power50-60% of 1RM (3-5 reps)

Lifting a lower number of reps at a lighter weight can help with promoting explosive power. Try to keep the breaks between your sets shorter.

Endurance~70% of 1RM (10-15 reps)

Lifting at around 70% of your 1RM for more repetitions helps promote muscle endurance.

Hypertrophy70-80% of 1RM (7-12 reps)

Lifting in this range can help with muscle growth (hypertrophy).

Strength80-100% of 1RM (1-3 reps)

Lifting in this range promotes a combination of muscle growth, power, and overall absolute strength. Use a spotter whenever possible.

Estimation Formulas

Epley Formula

W × (1 + Reps / 30)

Brzycki Formula

W × (36 / (37 - Reps))

Lombardi Formula

W × (Reps^0.10)

Medical 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. Do not attempt a 1 Rep Max lift without proper training, technique, and an experienced spotter.