Logo

onerepmax

One-Rep Max (1RM) Calculator

Enter a recent lift to estimate your one-rep max. Accurate, fast, and essential for strength programming.

Popular Exercises

Select an exercise to calculate specific standards

Chest

Bench Press

The bench press is a compound exercise that targets the muscles of the chest, shoulders, and triceps.

Legs

Squat

The squat is a lower body exercise used in strength training and bodybuilding that targets the thighs and glutes.

Back

Deadlift

The deadlift is a weight training exercise in which a loaded barbell or bar is lifted off the ground to the level of the hips.

Shoulders

Overhead Press

The overhead press constitutes a compound exercise that targets the shoulders and triceps.

Legs

Leg Press

The leg press is a compound weight training exercise for the legs performed on a machine.

Back

Barbell Row

The bent-over row is a weight training exercise that targets a variety of back muscles.

Chest

Incline Bench

The incline bench press is a variation of the bench press that targets the upper portion of the chest.

Legs

Front Squat

The front squat places the barbell on the front deltoids, shifting emphasis to the quadriceps and upper back.

Glutes

Hip Thrust

The hip thrust is a glute-dominant exercise performed with the back resting on a bench and a barbell across the hips.

Back

Weighted Pull-Up

A vertical pulling exercise where external weight is added to bodyweight.

Chest

Weighted Dip

A pushing exercise performed on parallel bars with added weight, targeting chest and triceps.

Legs

Trap Bar Deadlift

A deadlift variation using a hexagonal bar that reduces lumbar stress and allows for greater leg drive.

Back

Weighted Chin-Up

A supinated grip vertical pulling exercise adding external weight to bodyweight.

Full Body

Weighted Muscle-Up

An advanced calisthenics skill combining a pull-up and a dip, performed with added weight.

Legs

Weighted Pistol Squat

A unilateral squat performed on one leg with added weight.

Browse by Rep Count

23456789101112131415161718192021222324252627282930

Frequently Asked Questions

What is a 1RM (One-Repetition Maximum)?
Your one-repetition maximum (1RM) is the maximum amount of weight you can lift for a single repetition of a given exercise. It's a common measure of strength in weight training.
What is the best rep range for estimating 1RM?
For the most reliable estimate, we recommend testing with a weight you can lift for 3 to 5 reps. Calculations based on lower rep ranges are significantly more accurate because they rely closer to your true neuromuscular limit. As you exceed 10 reps, factors like metabolic fatigue (the 'burn') can skew the results, making the 1RM prediction less accurate.
What percentage of 1RM should I use for muscle growth?
To build Strength, train with 85-100% of your 1RM (1-5 reps). For Hypertrophy (Muscle Size), the optimal range is typically 70-85% of your 1RM (6-12 reps). For Endurance, use lighter loads of 50-70% (15+ reps). The 'Rep Max Breakdown' table in this calculator provides these exact numbers for you.
How accurate is this calculator?
This calculator uses the well-known Brzycki formula to estimate your 1RM. While it is a widely accepted standard in sports science, it is still an estimate. Individual factors like muscle fiber type, fatigue, and limb length can influence your true 1RM. For the most accurate result, perform a true 1RM test under safe conditions with spotters.
Why should I calculate my 1RM?
Knowing your 1RM helps you tailor your training program effectively. Many periodized strength and hypertrophy programs (like 5/3/1 or Smolov) are based on specific percentages of your 1RM. This data allows you to train at the exact intensity needed to achieve your specific fitness goals without guessing.
Which exercises does this work for?
The formula works best for compound lifts like Bench Press, Squat, Deadlift, and Overhead Press. It can be used for isolation exercises or machine weights, but accuracy may vary as isolation movements often allow for higher rep ranges where the formula becomes less precise.