One Rep Max Calculator (Lombardi Formula)

About the One Rep Max Calculator (Lombardi Formula)

The Lombardi formula uses a power-law relationship to estimate one-rep max, which makes it mathematically different from Epley and Brzycki.

This can make the estimate behave differently at moderate to higher rep counts. The calculator shows Lombardi alongside familiar comparisons so you can see how the projected max shifts across formulas.

It is mainly a comparison tool for rep-based max estimates rather than a single definitive answer.

When This Page Helps

It is useful when you want to see how a power-law model handles higher-rep sets. The result is best read alongside other formulas rather than treated as uniquely correct.

How to Use the Inputs

1. Perform a set to near failure.
2. Enter the weight lifted and reps completed.
3. View the Lombardi 1RM estimate.
4. Compare with Epley and Brzycki estimates shown alongside.
5. Use the percentage chart for training weights.

Example Calculation

Tips & Best Practices

• Lombardi shines with higher rep test sets (10–15 reps) where Epley and Brzycki lose accuracy.
• For low reps (1–5), all three formulas give very similar results — formula choice matters less.
• The power-law model assumes diminishing returns per additional rep, which aligns with most lifters' experience.
• Use the average of all three formulas for your training max — this is the most robust approach.
• Round down to the nearest 5 lbs when setting training weights for safety.

Power Laws in Strength Science

The Lombardi formula applies a power law, which is common in biological scaling. Many physical performance metrics (sprint speed, jump height, strength output) follow power-law relationships with body mass and training variables. The 0.10 exponent in Lombardi's formula captures the diminishing relationship between repetitions and maximal strength.

Three Formulas, One Truth

No formula perfectly predicts a true 1RM for every individual. The rep-max relationship varies by muscle group, fiber type composition, training history, and even psychological factors. Using all three major formulas (Epley, Brzycki, Lombardi) and averaging the results removes individual formula bias and has been shown to fall within 3–5% of actual 1RM in most trained individuals.

Practical Application: Conservative vs. Aggressive

If you need a training max (the number you base your program percentages on), use the lowest of the three formulas (usually Brzycki). If you want to know your likely true max for competition planning, use the average. Never use the highest formula estimate as your competition opener — that's a recipe for a missed lift.

Frequently Asked Questions

• When should I use Lombardi over Epley?

  Use Lombardi when your test set is 10+ reps. At this range, Epley tends to overestimate, while Lombardi's power-law curve provides a more realistic prediction. For sets of 1–8 reps, the formulas give similar enough results that the choice doesn't matter much.

• What does the 0.10 exponent mean?

  The exponent 0.10 means that reps have a diminishing effect on predicted max. Going from 1 to 2 reps increases the prediction more than going from 10 to 11 reps. This models the real-world phenomenon where each additional rep becomes progressively harder relative to the strength it represents.

• Is Lombardi more accurate than the other formulas?

  No single formula is universally "most accurate." Validation studies show that accuracy depends on the rep range, the exercise, the individual, and their training background. Lombardi tends to be more accurate at higher reps. The best practice is to use multiple formulas and take the average.

• Why are there so many different 1RM formulas?

  Each formula was developed from different data sets (different exercises, populations, and rep ranges). They all attempt to model the same relationship but make different mathematical assumptions. This is why comparing multiple formulas gives a more reliable estimate than relying on any single one.

• Does the formula work for all exercises?

  Like all 1RM formulas, Lombardi was primarily validated on compound barbell exercises. It can be applied to any resistance exercise, but accuracy may vary for isolation movements, machines, or exercises with unusual strength curves.

• Can Lombardi handle very high reps (20+)?

  Technically yes — unlike Brzycki, Lombardi has no mathematical breaking point. However, above 15–20 reps, all formulas become less reliable because muscular endurance, cardiovascular fitness, and mental fatigue increasingly dominate over pure strength. For practical purposes, test with 12 reps or fewer.