What is the Brzycki formula?

The Brzycki formula is: 1RM = Weight × (36 / (37 − Reps)). It was developed by Matt Brzycki and published in 1993. It is most accurate for sets of 2–10 reps and tends to overestimate at higher rep ranges.

How accurate is the Brzycki formula?

It is most accurate in the 6–10 rep range. For sets above 10 reps, the formula may overestimate your true 1RM because muscular endurance becomes a larger factor relative to maximal strength.

Should I use kg or lb?

The formula works with any unit. Just be consistent — if you enter weight in kg the result is in kg; in lb the result is in lb. The unit label updates automatically when you switch.

Can I use this for 1 rep?

At exactly 1 rep the formula returns the weight you entered, because that is by definition your 1RM for that set. Use at least 2 reps for a meaningful estimate.

What do the training percentages mean?

Strength coaches assign intensity zones by percentage of 1RM: 90–100% for maximal strength, 75–85% for strength/hypertrophy, 60–75% for hypertrophy/volume, and below 60% for endurance and warm-up work.

One Rep Max Calculator (Brzycki)

Enter the weight lifted and reps performed to estimate your 1RM using the Brzycki formula, then see a full training percentage table.

Your Lift Data

Unit

Weight lifted (kg)

Reps performed

Brzycki formula: 1RM = Weight × (36 ÷ (37 − Reps))
Most accurate for 2–10 reps.

Enter your weight and reps, then tap Calculate.

Training Percentage Table

% of 1RM	Load	Typical Reps	Zone

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Summary

The Brzycki formula estimates your theoretical one-repetition maximum (1RM) from a submaximal set — weight you can lift for 2 to 10 reps. It is one of the most widely used 1RM prediction equations in strength training because of its accuracy in the 6–10 rep range. Once your 1RM is known, the training table shows standard loading percentages (50%–100%) so you can plan intensity zones for strength, hypertrophy, and power work.

How it works

Enter the weight you lifted (in kg or lb) in the Weight field.
Enter the number of reps you completed with that weight.
The calculator applies the Brzycki formula: 1RM = Weight × (36 / (37 − Reps)).
Your estimated 1RM is displayed instantly.
The training table below shows recommended loads at 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, and 100% of your 1RM.

Use cases

Plan progressive overload by knowing exact weights for each intensity zone.
Set loading targets for powerlifting competition warm-ups.
Track strength progress over time without maxing out every session.
Program hypertrophy work at 65–75% 1RM with confidence.
Compare estimated 1RM across different exercises like squat, bench, and deadlift.
Guide beginner lifters on safe starting loads without attempting a true max.

Frequently Asked Questions

Last updated: 2026-05-29 · Reviewed by Nham Vu