What makes the Lombardi formula different from other 1RM equations?

Lombardi uses a fixed exponent of 0.10, which produces a gentler progression than formulas with linear or higher-order polynomial terms. This tends to yield more conservative estimates at higher repetition ranges compared to Epley or Brzycki equations.

Why does the formula use an exponent of 0.10?

The 0.10 exponent was derived empirically by Lombardi in 1989 from regression analysis of submaximal lift data. It reflects the average rate at which repetitions predict increases in estimated maximal load across the sample population studied.

Can this formula be used for any lift?

The Lombardi equation is exercise-agnostic in its mathematical structure, but accuracy varies by movement. Compound lifts with shorter ranges of motion (e.g., bench press, squat) tend to align more closely with the formula's assumptions than isolation exercises or movements with long eccentric phases.

How does fatigue affect the estimate?

Cumulative fatigue from prior sets, training sessions, or inadequate recovery can reduce the number of repetitions completed at a given weight, leading the formula to underestimate true 1RM. The equation assumes the submaximal set represents a near-maximal effort under rested conditions.

What repetition range produces the most reliable estimates?

Research comparing predicted and measured 1RM values suggests that sets of 3 to 8 repetitions typically yield estimates within 5–10% of actual maximal lifts when form is consistent and sets are taken to or near failure. Estimates from sets above 12 reps show greater variance.

Strength Training

One-Rep Max Calculator (Lombardi Formula)

Estimate your one-rep max from submaximal lifts using the Lombardi formula.

Last updated: 22 April 2026

What this tool does

This calculator estimates your one-rep max (1RM) from a submaximal lift using the Lombardi formula, published in 1989 and derived from resistance-trained populations. It accepts the weight lifted and the number of repetitions performed, then applies the equation 1RM = weight × reps^0.10 to produce an estimated maximal strength value in kilograms or pounds. The Lombardi method models each additional repetition's contribution to predicted 1RM through a fixed exponent, offering a population-average estimate suitable for programming and tracking progress in strength training.

Inputs

Result

—

Formula Used

1RM = w \times r^{0.10}

w

Weight in kg

r

Reps performed

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How One-Rep Max Calculator (Lombardi Formula) works

This calculator estimates a lifter's one-repetition maximum (1RM) by applying the Lombardi formula to a submaximal set. When a user enters the weight lifted and the number of repetitions completed, the tool multiplies the weight by the repetitions raised to the power of 0.10. The result is an estimated maximum load the lifter could handle for a single repetition.

The formula

The Lombardi equation is expressed as:

1RM = weight × reps^0.10

Where weight is the load lifted (in kilograms) and reps is the number of completed repetitions. The exponent of 0.10 reflects Lombardi's 1989 observation that each additional repetition contributes a predictable increment to maximum strength capacity.

Where this method is most accurate

The Lombardi formula tends to produce estimates closest to true 1RM when the repetition range falls between 2 and 10. Beyond 10 repetitions, the relationship between submaximal endurance and maximal strength becomes less linear, and local muscular endurance begins to dominate the lift. Sets performed to technical failure—where form breaks down before concentric failure—may also produce estimates that diverge from actual 1RM. The formula does not account for exercise type, tempo, rest intervals, or individual fiber-type distribution.

What this tool does not do

This calculator generates a mathematical estimate; it does not prescribe training loads, assess injury risk, or evaluate readiness to attempt a maximal lift. It does not replace supervised one-rep-max testing protocols used in research or competitive settings. The tool does not account for fatigue, hydration, sleep quality, or training history—all of which influence acute strength expression.

Disclaimer

This tool is for educational and informational purposes only. It is not medical, training, or health advice. No calculator output constitutes a recommendation to lift any specific load or undertake any training program. Users are responsible for their own training decisions and should consult qualified coaches or healthcare professionals when appropriate.

Questions

What makes the Lombardi formula different from other 1RM equations?: Lombardi uses a fixed exponent of 0.10, which produces a gentler progression than formulas with linear or higher-order polynomial terms. This tends to yield more conservative estimates at higher repetition ranges compared to Epley or Brzycki equations.
Why does the formula use an exponent of 0.10?: The 0.10 exponent was derived empirically by Lombardi in 1989 from regression analysis of submaximal lift data. It reflects the average rate at which repetitions predict increases in estimated maximal load across the sample population studied.
Can this formula be used for any lift?: The Lombardi equation is exercise-agnostic in its mathematical structure, but accuracy varies by movement. Compound lifts with shorter ranges of motion (e.g., bench press, squat) tend to align more closely with the formula's assumptions than isolation exercises or movements with long eccentric phases.
How does fatigue affect the estimate?: Cumulative fatigue from prior sets, training sessions, or inadequate recovery can reduce the number of repetitions completed at a given weight, leading the formula to underestimate true 1RM. The equation assumes the submaximal set represents a near-maximal effort under rested conditions.
What repetition range produces the most reliable estimates?: Research comparing predicted and measured 1RM values suggests that sets of 3 to 8 repetitions typically yield estimates within 5–10% of actual maximal lifts when form is consistent and sets are taken to or near failure. Estimates from sets above 12 reps show greater variance.

Sources & Methodology

Applies the Lombardi (1989) formula: 1RM = weight × reps^0.10. The exponent of 0.10 models the contribution of each additional repetition to estimated maximal strength. Originally derived from submaximal testing data in resistance-trained populations.

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