Free calculator
One rep max calculator
Enter a weight you lifted and how many reps you got. The calculator estimates your one rep max (1RM) and the weight to use for any other rep range.
- Use a hard set: one or two reps left at most.
- 10 reps or fewer gives the best estimate.
- Count only reps with good form.
Your training weights
Your 1RM is shown exactly. Every other weight is rounded to the nearest 2.5 kg so you can load it. Showing the example: 100 kg for 5 reps.
Percentages of your 1RM
| % of 1RM | Weight | Reps |
|---|---|---|
| 100% | 116.7 kg | 1 |
| 95% | 110 kg | about 2 |
| 90% | 105 kg | about 3 |
| 85% | 100 kg | about 5 |
| 80% | 92.5 kg | about 8 |
| 75% | 87.5 kg | about 10 |
| 70% | 82.5 kg | about 13 |
| 65% | 75 kg | 15+ |
| 60% | 70 kg | 15+ |
| 55% | 65 kg | 15+ |
| 50% | 57.5 kg | 15+ |
Rep maxes
| Reps | Weight |
|---|---|
| 1 (your 1RM) | 116.7 kg |
| 2 | 110 kg |
| 3 | 105 kg |
| 4 | 102.5 kg |
| 5 | 100 kg |
| 6 | 97.5 kg |
| 8 | 92.5 kg |
| 10 | 87.5 kg |
| 12 | 82.5 kg |
| 15 | 77.5 kg |
How the calculator works
It uses the Epley formula, the same one the Trayner app uses on the sets you log:
1RM = weight × (1 + reps ÷ 30)
For 100 kg lifted for 5 reps: 100 × (1 + 5 ÷ 30) = 116.7 kg. A single rep is taken as your 1RM as it stands.
The Brzycki formula, weight × 36 ÷ (37 − reps), is shown as a second opinion. Between 2 and 10 reps the two agree to within 4%. Past 10 reps they split, so a heavy set of 3 to 8 reps tells you more than a light set of 15.
Using the numbers
Most strength programmes are written as percentages: “3 sets of 5 at 80%” means 80% of your 1RM. Read the weight off the first table. The reps column is the Epley formula turned round, so it gives a rough ceiling, not a target. Leave a rep or two in reserve on most sets.
An estimate goes stale as you get stronger. Recalculate from a recent hard set every few weeks, and estimate each lift separately: a bench press number says nothing about your squat.
Trayner
Your 1RM, worked out from every set you log
Trayner estimates your 1RM from the sets you log, with the same formula as this calculator, and records a new best when it goes up. On seven lifts, including the bench press and Romanian deadlift, Form Check scores every rep you film.
Logging and personal records are free. Form Check is part of Pro, and your first 14 days include Pro with no card needed. How Form Check works · Plans
FAQ
1RM calculator questions
What is a one rep max (1RM)?
Your one rep max is the heaviest weight you can lift once, with good form, on a given exercise. Strength programmes often set training weights as a percentage of it, for example 5 sets of 5 at 80%.
How accurate is a 1RM calculator?
It gives an estimate, not a test result. Estimates are closest when the set was hard (you had no more than one or two reps left) and had 10 reps or fewer. Above 10 reps the formulas drift apart and the estimate becomes less reliable.
Which 1RM formula is best?
No formula suits everyone. This calculator uses the Epley formula and shows the Brzycki formula alongside it. Between 2 and 10 reps the two stay within 4% of each other; by 15 reps they are 8% apart, which is why a set of 3 to 8 reps gives a more useful estimate than a set of 15.
Do I need to test my real one rep max?
No. Most lifters train well from an estimate. If you do test a true max, warm up thoroughly, work up in small jumps, and use a spotter or safety bars on the bench press and squat.
Can I use it in pounds?
Yes. Switch the unit to lb. Training weights are rounded to the nearest 5 lb, or to the nearest 2.5 kg in kilograms, so they can be loaded on a bar. Your 1RM itself is shown exactly.
Does it work for every exercise?
It works best for the main barbell lifts, such as the squat, bench press, deadlift and overhead press. For machines and single-joint exercises, rep-based estimates tend to be less reliable, so treat the number as a rough guide.
Can Trayner work out my 1RM for me?
Yes. Trayner estimates your 1RM from the sets you log, using the same Epley formula as this calculator, and records a new best when it goes up. Logging and personal records are on the free plan.