Lombardi Formula: 1RM Calculator and Complete Guide
The Lombardi formula estimates 1RM using weight × reps^0.10, a logarithmic model that tends to be more conservative than linear formulas and works well for experienced lifters.
Strength Training Researcher
Published · Last reviewed · 6 min read
Lombardi formula calculator
Single-formula calculator. For an averaged estimate across all 7 formulas, use the main calculator.
History and origin
V. Patteson Lombardi, an exercise scientist at the University of Oregon, introduced his power-function 1RM formula in his 1989 textbook "Beginning Weight Training: The Safe and Effective Way." Unlike linear formulas, Lombardi uses a logarithmic power function — 1RM = weight × reps^0.10 — that more closely models how trained lifters' rep capacity scales with load. The formula tends to be more conservative than Epley or Brzycki at high rep counts and slightly more aggressive at very low reps. Strength coaches working with experienced powerlifters often prefer Lombardi because it accounts for the higher relative strength (closer rep-to-1RM ratio) seen in well-trained athletes.
Lombardi, V.P. (1989). Beginning Weight Training: The Safe and Effective Way. Dubuque, IA: William C. Brown.
When to use the Lombardi formula
Best for
Experienced powerlifters, athletes with high neuromuscular efficiency
Limitation
Tends to underestimate for beginners with lower neural drive
Compared to other formulas
Compared to linear formulas like Epley and O'Conner, Lombardi produces lower 1RM estimates in the 8-15 rep range — better matching the slower rep drop-off seen in advanced lifters. At low reps (1-3), Lombardi tracks closely with Epley and Brzycki. The formula is particularly useful as a "second opinion" against linear models for trained athletes; if Epley and Lombardi disagree by more than 5%, the truth is usually closer to Lombardi.
How to use the Lombardi formula (step by step)
- Perform a heavy submaximal set. Perform a clean set of 2-10 reps to near-failure (RPE 8-9) on the lift you want to test. Record the weight and the rep count.
- Apply the Lombardi equation.
1RM = weight × reps^0.10 - Read the estimated 1RM. The output is your estimated 1RM. For programming, multiply by 0.9 to derive your Training Max — this absorbs daily strength variability and reduces overshoot risk.
- Cross-check against other formulas. Run the same numbers through every other formula and compare. The main calculator does this automatically using a trimmed mean.
Worked examples — Lombardi formula
Computed with the Lombardi formula. Compare these single-formula estimates against the trimmed-mean average from our main calculator.
| Set | Weight × Reps | Lombardi 1RM (lb) |
|---|---|---|
| Example 1 | 135 lb × 12 | 173 lb |
| Example 2 | 185 lb × 8 | 228 lb |
| Example 3 | 225 lb × 5 | 264 lb |
| Example 4 | 315 lb × 3 | 352 lb |
| Example 5 | 405 lb × 2 | 434 lb |
How Lombardi compares to the other six formulas
The same submaximal set — 225 lb × 5 reps — produces different 1RM estimates depending on which formula you use. Here are all seven, side by side:
| Formula | Estimated 1RM | vs Lombardi |
|---|---|---|
| Epley | 263 lb | -1 lb |
| Brzycki | 253 lb | -11 lb |
| Lombardithis page | 264 lb | — |
| O'Conner | 253 lb | -11 lb |
| Mayhew | 268 lb | +4 lb |
| Wathan | 262 lb | -2 lb |
| Lander | 256 lb | -8 lb |
See the full formula comparison page for accuracy data and decision-making guidance.
Lombardi reverse lookup: target 1RMs at common rep ranges
Working backward from a target 1RM, here's the working weight you would need to lift for various rep counts to predict that max via the Lombardi formula. Use this to set training targets for blocks aimed at hitting a specific number.
| Target 1RM | 3 reps | 5 reps | 8 reps | 10 reps |
|---|---|---|---|---|
| 200 lb | 179 lb | 170 lb | 162 lb | 159 lb |
| 300 lb | 269 lb | 255 lb | 244 lb | 238 lb |
| 400 lb | 358 lb | 341 lb | 325 lb | 318 lb |
| 500 lb | 448 lb | 426 lb | 406 lb | 397 lb |
Round to the nearest 5 lb when programming. For competition-style peaking, see the 5/3/1 calculator or RPE programming.
Validation research
The Lombardi formula has been evaluated in multiple peer-reviewed studies of 1RM prediction accuracy. Selected findings:
Mayhew, Wathan, and Brzycki produced the smallest error across bench, squat, and deadlift. Most formulas underestimated 1RM as reps increased.
LeSuer, D.A., McCormick, J.H., Mayhew, J.L., Wasserstein, R.L., & Arnold, M.D. (1997). The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. Journal of Strength and Conditioning Research, 11(4), 211-213.
Standard error of estimate ranged from 5.6 to 7.9 kg across formulas; high reps (>10) reduced accuracy meaningfully.
Reynolds, J.M., Gordon, T.J., & Robergs, R.A. (2006). Prediction of one repetition maximum strength from multiple repetition maximum testing and anthropometry. Journal of Strength and Conditioning Research, 20(3), 584-592.
In older adults, most formulas overestimated 1RM by 5-15%; conservative choices (Lander, O'Conner) outperformed.
Wood, T.M., Maddalozzo, G.F., & Harter, R.A. (2002). Accuracy of seven equations for predicting 1-RM performance of apparently healthy, sedentary older adults. Measurement in Physical Education and Exercise Science, 6(2), 67-94.
Lombardi Formula FAQ
Further reading & authoritative sources
These external sources informed the content on this page. Authoritative references are a hallmark of trustworthy strength training information; we link directly so you can verify and explore further.
- Wikipedia: One-repetition maximum
General reference for the 1RM concept and major prediction formulas.
- Essentials of Strength Training and Conditioning (NSCA, Human Kinetics)
The CSCS textbook chapter on load assignment includes the formulas covered here.
- LeSuer et al. (1997) — Accuracy of 1RM prediction equations
Foundational comparative study of 1RM prediction equation accuracy.
- Stronger by Science — Greg Nuckols, evidence-based training research
Greg Nuckols’ evidence-based commentary on rep-to-1RM relationships.
- OpenPowerlifting — global meet results database
Real-world meet results database for sanity-checking calculator output.
References
- Original publication: Lombardi, V.P. (1989). Beginning Weight Training: The Safe and Effective Way. Dubuque, IA: William C. Brown.
- LeSuer et al. (1997): LeSuer, D.A., McCormick, J.H., Mayhew, J.L., Wasserstein, R.L., & Arnold, M.D. (1997). The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. Journal of Strength and Conditioning Research, 11(4), 211-213.
- Reynolds et al. (2006): Reynolds, J.M., Gordon, T.J., & Robergs, R.A. (2006). Prediction of one repetition maximum strength from multiple repetition maximum testing and anthropometry. Journal of Strength and Conditioning Research, 20(3), 584-592.
- Wood et al. (2002): Wood, T.M., Maddalozzo, G.F., & Harter, R.A. (2002). Accuracy of seven equations for predicting 1-RM performance of apparently healthy, sedentary older adults. Measurement in Physical Education and Exercise Science, 6(2), 67-94.
- Wikipedia: One-repetition maximum — general reference for 1RM prediction equations.
- Essentials of Strength Training and Conditioning (NSCA, Human Kinetics) — NSCA CSCS textbook chapter on load assignment.