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Your one-rep max, without the guesswork.
Enter a weight and a rep count. We average five validated formulas — Epley, Brzycki, Lombardi, O'Conner, and Wathan — to estimate what you could lift for a single rep. No sign-in. No ads. Use it before your next session.
Estimated 1RM
260lb
Average of five formulas, rounded to the nearest plate you can load.
Per-formula breakdown
Epley
265 lb
Brzycki
255 lb
Lombardi
265 lb
O'Conner
255 lb
Wathan
260 lb
Training percentages
Bench Press
| % of 1RM | Weight | Typical reps |
|---|---|---|
| 95% | 245 lb | 2 |
| 90% | 235 lb | 3–4 |
| 85% | 220 lb | 5–6 |
| 80% | 205 lb | 7–8 |
| 75% | 195 lb | 9–10 |
| 70% | 180 lb | 11–12 |
| 65% | 170 lb | 13–14 |
| 60% | 155 lb | 15–16 |
| 55% | 140 lb | 17–19 |
| 50% | 130 lb | 20+ |
| 45% | 115 lb | Warmup |
| 40% | 105 lb | Warmup |
Rep ranges are approximations for a trained lifter. Your mileage varies with conditioning, technique, and the lift itself.
Track every rep, not just the calculation.
Wodder logs your sets, flags real PRs, and updates your training max automatically. Free to start.
What is a one-rep max?
Your one-rep max — 1RM for short — is the heaviest weight you can lift for a single, technically clean repetition. It is the yardstick programmers use to prescribe training weights. A percentage-based program that tells you to squat 80% for five reps is meaningless without a number to scale from.
Testing a true 1RM is taxing, risky, and often unnecessary. A sound estimate from a set of three to eight reps tells you almost everything you need for programming, and it costs you nothing.
How the calculator works
We compute five well-studied rep-to-max formulas and average the results. No single formula is universally accurate, but the average of five cancels out most of the drift that shows up when you use only one.
- Epley — the workhorse. Popular for its simplicity:
w × (1 + reps / 30). - Brzycki — conservative for high reps; used widely in strength literature.
- Lombardi — mild curve, tracks well through the middle range.
- O'Conner — linear, cautious; favored by physical-therapy research.
- Wathan — the most accurate for most lifters at low-to-moderate reps.
Past 10 reps, every formula breaks down. Endurance becomes the limiting factor, not strength. Keep your test set in the three-to-eight range for a meaningful number.
When should you test a real max?
Rarely. Maybe once or twice a year for a powerlifting peak, or before a competition. For everyone else, an estimate is enough. Your training max — the number your program actually uses — should sit around 85–90% of your calculated 1RM. That buffer keeps every rep crisp and every session repeatable.
Which formula is the most accurate?
Wathan tends to win in direct comparisons against measured maxes, especially in the three-to-six rep range. Epley runs slightly high on taxing sets. Brzycki undershoots at high reps. The average is always closer than any single formula alone — which is why we use the average.
Caveats
A 1RM estimate assumes a set taken to technical failure — the last rep was grindy, and one more would have been a miss. If you stopped two reps shy, your real max is higher than this tool will show. If your form broke down before failure, your number is inflated. Be honest with yourself; the calculator cannot be.
Your maxes live in the work, not the math.
Wodder logs every set, tracks every lift, and tells you the moment you hit a real PR — estimated or tested. Free forever plan. No credit card.