What is a 1RM?
Your one-rep max is the most weight you can lift for one full repetition of an exercise with good form. It is the standard measure of maximal strength, and most strength programs set training weights as a percentage of it - "5 sets of 5 at 80%" means 80% of your 1RM.
Testing a true max is taxing and riskier than a normal training set, so most lifters estimate it instead. A hard set of several reps carries enough information to predict what you could lift once.
How this calculator works
Your set runs through seven published 1RM prediction equations. The big number is their average, and the formula breakdown shows each equation's result so you can see the spread. A single rep is taken as your 1RM as-is.
- Use a hard set. The estimate assumes you took the set close to failure. Stopping well short of failure underestimates your 1RM.
- Keep it to 10 reps or fewer. The equations stay reasonably close up to about 10 reps and diverge quickly after that, which is why the calculator accepts at most 15.
- Estimate each lift separately. Your bench press, squat and deadlift maxes are independent, so estimate each one from its own set.
1RM formulas
Where w is the weight lifted and r is the number of reps completed:
| Formula | 1RM equation |
|---|---|
| Epley | w × (1 + r ÷ 30) |
| Brzycki | w × 36 ÷ (37 − r) |
| Lander | 100 × w ÷ (101.3 − 2.67123 × r) |
| Lombardi | w × r^0.10 |
| Mayhew et al. | 100 × w ÷ (52.2 + 41.9 × e^(−0.055 × r)) |
| O'Conner et al. | w × (1 + 0.025 × r) |
| Wathan | 100 × w ÷ (48.8 + 53.8 × e^(−0.075 × r)) |
Percent of 1RM chart
How many reps you can typically complete at each percentage of your 1RM, from the NSCA's percent-of-1RM table (Essentials of Strength Training and Conditioning). Use it to pick working weights or to sanity-check an estimate. Individual results vary with the exercise and your training history.
| % of 1RM | Reps you can typically complete |
|---|---|
| 100% | 1 |
| 95% | 2 |
| 93% | 3 |
| 90% | 4 |
| 87% | 5 |
| 85% | 6 |
| 83% | 7 |
| 80% | 8 |
| 77% | 9 |
| 75% | 10 |
| 70% | 11 |
| 67% | 12 |
| 65% | 15 |
How to use your 1RM in training
Training load guidelines from the NSCA, by goal:
| Goal | Load | Reps per set |
|---|---|---|
| Strength | 85% or more | 6 or fewer |
| Muscle size (hypertrophy) | 67-85% | 6-12 |
| Muscular endurance | 67% or less | 12 or more |
Treat the estimate as a starting point: if a prescribed weight feels far too easy or impossible for the reps, adjust it and re-estimate from that set.
How does your 1RM compare?
What counts as strong depends on your bodyweight, sex, age and experience. See where your numbers land in our strength standards by bodyweight, or compare with the average bench press and average squat and deadlift by age.
Testing your 1RM safely
- Warm up with several progressively heavier sets of low reps before any heavy single.
- Use a spotter or safety bars on the bench press and squat.
- Rest a few minutes between heavy attempts, and stop when your form breaks down.
- If you have an injury or medical condition, check with a qualified professional before testing a max.
Track your estimated 1RM automatically
Gainwise, the workout tracker that coaches you, tracks your estimated 1RM and personal records from the sets you log, so you can watch your strength climb without testing a max. Launching soon on iPhone.
Frequently Asked Questions
How accurate is a 1RM calculator?
It gives an estimate, not a measurement. Estimates from a set of about 10 reps or fewer, taken close to failure with good form, are the most dependable. Past that the formulas disagree more, and your true max also depends on the exercise, your technique and how practiced you are at heavy singles.
Which 1RM formula is the most accurate?
No single formula is best for everyone. Epley and Brzycki are the most widely used, but each equation comes from a different study, so this calculator shows all seven and uses their average as your estimated 1RM.
What percentage of my 1RM should I train with?
It depends on your goal. NSCA guidelines put strength work at 85% of 1RM or more for 6 reps or fewer, muscle-building (hypertrophy) work at 67-85% for 6-12 reps, and muscular endurance work at 67% or less for 12 or more reps.
How often should I test my 1RM?
Many programs retest at the end of a training block, often every 8-12 weeks. In between, estimating your 1RM from regular working sets tracks your progress without the fatigue of a max attempt.
Does the calculator work in kilograms and pounds?
Yes. The formulas work the same in any unit: enter the weight in the unit you lifted it in, pick lb or kg, and every result comes back in that unit.
What is a good 1RM?
It depends on your bodyweight, sex, age and training experience. Our strength standards break down typical one-rep maxes for the bench press, squat and deadlift. See the strength standards.