Calculate your 1RM using the Lombardi formula. Better accuracy at higher rep ranges than Epley or Brzycki. Enter weight and reps for your estimate.
The Lombardi formula uses a power-law relationship to estimate one rep max, making it mathematically distinct from both Epley (linear) and Brzycki (hyperbolic). The formula multiplies the weight by reps raised to the 0.10 power, which produces a gradually increasing curve.
This power-law approach has a theoretical advantage at higher rep ranges (10–20 reps) because it models the diminishing relationship between additional reps and predicted strength better than linear formulas. At low reps (1–5), it converges with Epley and Brzycki.
Comparing results across all three formulas gives you a range that likely brackets your true 1RM. This calculator shows the Lombardi result alongside Epley and Brzycki comparisons. Whether you are a beginner or experienced professional, this free online tool provides instant, reliable results without manual computation. By automating the calculation, you save time and reduce the risk of costly errors in your planning and decision-making process. This tool handles all the complex arithmetic so you can focus on interpreting results and making informed decisions based on accurate data.
The Lombardi formula offers better accuracy at higher rep ranges (10–20) than Epley or Brzycki. Use it when your test set includes more than 10 reps, or compare all three formulas for a more reliable estimate. Having a precise figure at your fingertips empowers better planning and more confident decisions.
Lombardi Formula: 1RM = weight × reps^0.10 Example: 225 lbs × 5^0.10 = 225 × 1.1746 = 264.3 lbs The power-law exponent of 0.10 means each doubling of reps adds about 7% to the predicted max.
Result: Lombardi: 264.3 lbs | Epley: 262.5 lbs | Brzycki: 253.1 lbs
At 5 reps, the three formulas give a range of 253–264 lbs. Lombardi and Epley are close (within 2 lbs), while Brzycki is more conservative. This 11-lb spread (4.4%) represents typical inter-formula variability. Your true 1RM likely falls within this range, with the average (~260 lbs) being the best single estimate.
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.
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.
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.
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.
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.
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.
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.
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.
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.