100 kg for 5 reps
Estimated 1RM of 115.5 kg. 90% is 104.0 kg, for about 4 reps.
One-rep max calculator
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Your one-rep max is estimated from a set taken close to failure, using the average of the Epley, Brzycki and Lombardi formulas. Estimates are most reliable from sets of 2 to 10 reps; above 12 they drift. Test a true single only with a spotter and a proper warm-up.
Unit
Estimated one-rep max
115.5 kg
100.0 kg for 5 reps suggests you could lift about 115.5 kg once. The three formulas range from 112.5 kg to 117.5 kg.
- Epley
- 116.7 kg
- Brzycki
- 112.5 kg
- Lombardi
- 117.5 kg
- In pounds
- 254.7 lb
Epley116.7 kg
Brzycki112.5 kg
Lombardi117.5 kg
Training weights from your one-rep max
| % of 1RM | Weight | Typical reps |
|---|---|---|
| 100% | 115.5 kg | 1 |
| 95% | 109.8 kg | 2 |
| 90% | 104.0 kg | 4 |
| 85% | 98.2 kg | 6 |
| 80% | 92.4 kg | 8 |
| 75% | 86.7 kg | 10 |
| 70% | 80.9 kg | 12 |
| 65% | 75.1 kg | 15 |
| 60% | 69.3 kg | 20 |
| 55% | 63.5 kg | Warm-up |
| 50% | 57.8 kg | Warm-up |
Getting a max without maxing out
A one-rep max, or 1RM, is the most you can lift once with good form. Strength programmes are written as percentages of it, so you need the number even if you never attempt a true single. The easy way is to estimate it from a set you already do.
Say you bench 100 kg for 5 hard reps. Epley gives 116.7 kg, Brzycki 112.5 kg and Lombardi 117.5 kg. The average is 115.5 kg, so a working set at 90% would be about 104 kg for around 4 reps, and 80% about 92 kg for around 8.
The estimate is only as good as the set. Count only clean reps, stop when form breaks, and use a set of 2 to 10 reps. A set of 20 tells you more about endurance than strength, and the formulas start to disagree.
Use the percentage table to plan, then let the bar decide. If 85% moves faster than expected, your max has gone up. Re-check every few weeks with a fresh hard set rather than testing a single each time.
Sources
What this calculator does not account for
- Sets above 12 reps, where the formulas spread.
- Lifts done with poor form or rest pauses.
- Differences between bench, squat and deadlift.
How this is calculated
Formula: Three common 1RM formulas
Epley: w × (1 + r ÷ 30); Brzycki: w × 36 ÷ (37 − r); Lombardi: w × r^0.10What the symbols mean
- wWeight lifted in the set.
- rReps completed with good form, close to failure.
Good to know
- The tool shows the average of the three, which smooths out where they disagree.
- Training weights are a percentage of that average.
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Worked examples
Each example is worked out by the same code as the calculator above.
Same lift in pounds: 225 lb for 5
About 260 lb estimated max.
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<iframe src="/embed/one-rep-max-calculator" title="One-rep max" width="100%" height="720" style="border:0;max-width:42rem" loading="lazy"></iframe>Questions
How do I calculate my one rep max?
Do a hard set of 2 to 10 reps, then put the weight and reps into a formula such as Epley: weight × (1 + reps ÷ 30). This tool averages three formulas.
Which 1RM formula is most accurate?
None is best for everyone. Epley and Brzycki agree closely at about 5 reps; Brzycki reads lower and Lombardi higher at high reps. Averaging them is a fair middle.
Is it safe to test a true one rep max?
It can be, with a proper warm-up, a spotter or safety bars, and good technique. Beginners get most of the benefit from estimated maxes without the risk.
What percentage of my max should I train at?
Roughly 85% and up for strength (1 to 6 reps), 67% to 85% for muscle size (6 to 12 reps) and lower for endurance work.
Why does my estimate change with high reps?
Above about 12 reps endurance matters more than strength, so the formulas spread apart. Use a heavier set for a better estimate.