1RM Calculator
Estimate your one-rep max from any sub-maximal set. Free, no signup, works for bench press, squat, deadlift, or any lift.
1RM Calculator
Estimate your one-rep max from any sub-maximal set.
Estimated 1RM
115 kg
Average of Epley, Brzycki, Lombardi & O'Conner formulas
Show all four formula results
Epley
117.5 kg
Brzycki
112.5 kg
Lombardi
117.5 kg
O'Conner
112.5 kg
Training percentages
| % 1RM | Weight (kg) | Reps |
|---|---|---|
| 100% | 115 | 1 |
| 95% | 110 | 2 |
| 90% | 102.5 | 3-4 |
| 85% | 97.5 | 5-6 |
| 80% | 92.5 | 8 |
| 75% | 85 | 10 |
| 70% | 80 | 12 |
| 65% | 75 | 15 |
| 60% | 70 | 18-20 |
| 50% | 57.5 | 20+ |
Track every PR automatically with Gainflow
Free workout tracker with AI form analysis. No paywall on core features.
What is a 1RM (One-Rep Max)?
Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition with proper form. It's the gold-standard measure of strength for any lift — bench press, squat, deadlift, overhead press — and the foundation for almost every serious strength program (5/3/1, Wendler, Sheiko, conjugate, you name it).
Testing a true 1RM is risky and exhausting. So instead, we estimate it from a set you've already done. If you can squat 100 kg for 5 reps, the math says your 1RM is around 113 kg. That estimate is what this calculator gives you — and what nearly every coach uses for programming.
How the calculator works
We use four established 1RM formulas and average them — single formulas tend to over- or under-shoot, the average lands closest to reality across most rep ranges.
- Epley: 1RM = w × (1 + reps / 30) — most accurate for 1–10 reps
- Brzycki: 1RM = w × (36 / (37 - reps)) — better for lower rep counts
- Lombardi: 1RM = w × reps^0.10 — works well at higher reps
- O'Conner: 1RM = w × (1 + reps / 40) — conservative estimate
What about the percentage table?
The percentage table tells you how much weight to use for different training goals. 85–95% is strength territory. 70–80% is the sweet spot for hypertrophy (muscle growth). 60–70% works for endurance and conditioning. Use these numbers to program your next mesocycle.
Embed this calculator on your site
Run a fitness blog, gym site, or coaching page? Embed this calculator for free — just copy the snippet below. Attribution is appreciated but not required.
<iframe src="https://www.gainflow.app/embed/1rm-calculator" width="100%" height="900" frameborder="0" style="border: 0; max-width: 600px;" title="1RM Calculator by Gainflow"></iframe>Stop guessing your 1RM — let Gainflow track it for you
Gainflow auto-estimates your 1RM from every working set, tracks PRs automatically, and shows your strength progression on clear charts. No paywall on the basics.