One rep max calculator (1RM)
Enter the weight and reps of a hard set you did. The calculator estimates your one rep max (1RM), the most you could lift for a single rep, and shows the weights to use for 1 to 12 reps. Works in kg or lb.
Your estimated 1RM
From 100 kg × 5 reps, Epley formula.
Estimates get less accurate above 10 reps. A heavier set of 3 to 6 reps gives a better number.
An estimate, not a test. It is most accurate from a hard set of 3 to 6 reps.
1RM chart: weights for 1 to 12 reps
| Reps | Weight | % of 1RM |
|---|---|---|
| 1 | 117.5 kg | 100% |
| 2 | 110 kg | 94% |
| 3 | 105 kg | 91% |
| 4 | 102.5 kg | 88% |
| 5 | 100 kg | 86% |
| 6 | 97.5 kg | 83% |
| 7 | 95 kg | 81% |
| 8 | 92.5 kg | 79% |
| 9 | 90 kg | 77% |
| 10 | 87.5 kg | 75% |
| 11 | 85 kg | 73% |
| 12 | 82.5 kg | 71% |
Percentages of your 1RM
| % of 1RM | Weight |
|---|---|
| 100% | 117.5 kg |
| 95% | 110 kg |
| 90% | 105 kg |
| 85% | 100 kg |
| 80% | 92.5 kg |
| 75% | 87.5 kg |
| 70% | 82.5 kg |
| 65% | 75 kg |
| 60% | 70 kg |
| 55% | 65 kg |
| 50% | 57.5 kg |
Compare formulas
| Formula | Estimated 1RM |
|---|---|
| Epley | 116.7 kg |
| Brzycki | 112.5 kg |
| Lombardi | 117.5 kg |
| Mayhew | 119 kg |
| O'Connor | 112.5 kg |
| Wathan | 116.6 kg |
| Lander | 113.7 kg |
| Average | 115.5 kg |
How to use the one rep max calculator
- Pick a recent hard set of one lift: the weight, and the reps you did with good form.
- If you stopped before failure, add how many more reps you could have done (reps in reserve).
- Read your estimated 1RM, then use the chart to pick a weight for the reps in your plan.
- Check it again every 4 to 8 weeks with a new hard set.
Write your training weights down: the free printable workout log has room for every set.
Which 1RM formula should you use?
Every formula turns a set of several reps into an estimated single. They give similar numbers at low reps and drift apart as the reps climb. Epley is the default here. Brzycki gives the same result at 10 reps, a lower one below 10 and a higher one above. A study that compared seven of these formulas in 67 college students found that only Mayhew and Wathan came close to real bench press maxes, only Wathan to real squat maxes, and that all seven underestimated the deadlift (LeSuer and colleagues, 1997). The practical rule: pick one formula and stick with it, so your numbers stay comparable.
Epley: 1RM = w × (1 + r ÷ 30)Brzycki: 1RM = w × 36 ÷ (37 − r)Lombardi: 1RM = w × r^0.10Mayhew: 1RM = 100 × w ÷ (52.2 + 41.9 × e^(−0.055 × r))O'Connor: 1RM = w × (1 + 0.025 × r)Wathan: 1RM = 100 × w ÷ (48.8 + 53.8 × e^(−0.075 × r))Lander: 1RM = 100 × w ÷ (101.3 − 2.67123 × r)
w is the weight lifted and r is the reps, plus any reps in reserve. For a single, the calculator returns the weight itself.
How to use your 1RM in training
| Goal | Reps per set | About % of 1RM |
|---|---|---|
| Strength | 1 to 5 | 85 to 100% |
| Muscle | 6 to 12 | 70 to 85% |
| Muscular endurance | 15 to 20 | 60 to 67% |
The percentages come from the Epley formula. Muscle grows across a wide range of reps when sets end close to failure, so treat these as starting points. If a plan says "3 × 5 at 80%", find 80% in the percentages table and round to the plates you have.
Get an accurate estimate
- Use a set of 3 to 6 reps. Above 10 reps, the estimate gets less reliable.
- Count only reps with good form and a full range of motion.
- Use a fresh set from early in the session, not your last set of the day.
- Be honest about reps in reserve. If you are not sure, leave it at 0.
- Compare like with like: a pause, a belt or a different bar all change the number.
Should you test a real 1RM?
You rarely need to. A true max is a skill of its own, and an estimate from a hard set of 3 to 6 reps is close enough to plan your training. If you want a real single, warm up well, work up in small jumps, use a spotter or safety bars, and stop when the bar slows down a lot or your form changes.
Track every lift in Gym Commitment
A 1RM is a snapshot. Gym Commitment keeps the story: last time's numbers sit in every set, a new best gets a trophy on the set that beat it, and every lift gets its own chart. Free to use, no account. Pro is optional and opens your full history.
One rep max calculator by lift
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One rep max calculator FAQ
How accurate is a one rep max calculator?
Close enough to plan your training when you use a hard set of 3 to 6 reps, but not exact. Accuracy drops above 10 reps and varies by lift and by person.
Which 1RM formula is best?
No formula is best for everyone. Epley and Brzycki are the most used and give similar numbers at low reps. If your estimates keep coming out high or low against real singles, switch formula, then stick with it so your numbers stay comparable.
Can I calculate my 1RM in pounds?
Yes. Switch the unit to lb. Training weights round to 5 lb by default, and you can change that to 2.5 or 10.
What does reps in reserve mean?
Reps in reserve (RIR) is how many more reps you could have done before failure. If you stopped a set of 5 with 2 reps left, the calculator treats it as about 7 reps to failure.
How often should I re-check my 1RM?
Every 4 to 8 weeks is plenty. Enter a recent hard set: if the number went up, your training is working.