One Rep Max Calculator
Your one-rep max (1RM) is the heaviest weight you can lift once with good form. Enter the weight and reps from a hard set, and this calculator estimates your 1RM with six published formulas, averages them and turns the result into training loads from 50% to 100%.
By the Calculators With Steps team · Updated November 10, 2026 · How we check our math
- Epley
- 116.7 kgw × (1 + r ÷ 30)
- Brzycki
- 112.5 kgw × 36 ÷ (37 − r)
- Lombardi
- 117.5 kgw × r^0.10
- O'Conner
- 112.5 kgw × (1 + 0.025 × r)
- Wathen
- 116.6 kg100 × w ÷ (48.8 + 53.8 × e^(−0.075 × r))
- Mayhew
- 119 kg100 × w ÷ (52.2 + 41.9 × e^(−0.055 × r))
Step-by-step working
- Epley: 100 × (1 + 5 ÷ 30) = 116.67 kg
- Brzycki: 100 × 36 ÷ (37 − 5) = 112.5 kg
- Lombardi: 100 × 5^0.10 = 117.46 kg
- O'Conner: 100 × (1 + 0.025 × 5) = 112.5 kg
- Wathen: 100 × 100 ÷ (48.8 + 53.8 × e^(−0.075 × 5)) = 116.58 kg
- Mayhew: 100 × 100 ÷ (52.2 + 41.9 × e^(−0.055 × 5)) = 119.01 kg
- Average = (116.67 + 112.5 + 117.46 + 112.5 + 116.58 + 119.01) ÷ 6 = 115.79 kg
Training loads from your 1RM
| % of 1RM | Weight | Approx. max reps | Typical use |
|---|---|---|---|
| 100% | 115.8 kg | 1 | Max strength (≤ 6 reps) |
| 95% | 110 kg | 2 | Max strength (≤ 6 reps) |
| 90% | 104.2 kg | 4 | Max strength (≤ 6 reps) |
| 85% | 98.4 kg | 6 | Max strength (≤ 6 reps) |
| 80% | 92.6 kg | 8 | Hypertrophy (6–12 reps) |
| 75% | 86.8 kg | 10 | Hypertrophy (6–12 reps) |
| 70% | 81.1 kg | 12 | Hypertrophy (6–12 reps) |
| 65% | 75.3 kg | More than 12 | Muscular endurance (12+ reps) |
| 60% | 69.5 kg | More than 12 | Warm-up, technique, endurance |
| 55% | 63.7 kg | More than 12 | Warm-up, technique, endurance |
| 50% | 57.9 kg | More than 12 | Warm-up, technique, endurance |
Estimates are most accurate from sets of 2–10 reps and differ between lifts and people. Rep counts in the table are from the NSCA training load chart; below 70% of 1RM they vary widely. Always warm up and use a spotter or safety bars for heavy sets.
How to use the one rep max calculator
- Choose kilograms or pounds.
- Enter the weight you lifted and the number of reps you completed with good form. Use a set taken close to failure, ideally between 2 and 10 reps.
- Read your estimated 1RM, the result from each formula and a table of training loads.
If you enter 1 rep, the weight itself is your 1RM. The calculator accepts up to 12 reps and warns you above 10, because accuracy drops as reps go up.
One rep max formulas
Each formula uses the weight lifted (w) and the reps completed (r):
| Formula | Equation |
|---|---|
| Epley (1985) | w × (1 + r ÷ 30) |
| Brzycki (1993) | w × 36 ÷ (37 − r) |
| Lombardi (1989) | w × r^0.10 |
| O’Conner et al. (1989) | w × (1 + 0.025 × r) |
| Wathen (1994) | 100 × w ÷ (48.8 + 53.8 × e^(−0.075 × r)) |
| Mayhew et al. (1992) | 100 × w ÷ (52.2 + 41.9 × e^(−0.055 × r)) |
The headline number is the average of all six, which smooths out the differences between them. The step-by-step working under the result shows each calculation.
Worked example: 100 kg for 5 reps
| Formula | Estimated 1RM |
|---|---|
| Epley | 116.7 kg |
| Brzycki | 112.5 kg |
| Lombardi | 117.5 kg |
| O’Conner | 112.5 kg |
| Wathen | 116.6 kg |
| Mayhew | 119.0 kg |
| Average | 115.8 kg |
The estimates range from 112.5 to 119 kg. That spread is normal and is a good reminder that any estimate can be a few percent off your true max.
Training loads by percentage of 1RM
Once you know your 1RM, you can set loads for any rep range. The approximate rep counts below come from the NSCA training load chart. For the 115.8 kg example:
| % of 1RM | Weight | Approx. max reps | Typical use |
|---|---|---|---|
| 100% | 115.8 kg | 1 | Max strength |
| 90% | 104.2 kg | 4 | Max strength |
| 85% | 98.4 kg | 6 | Max strength |
| 80% | 92.6 kg | 8 | Hypertrophy |
| 75% | 86.8 kg | 10 | Hypertrophy |
| 70% | 81.1 kg | 12 | Hypertrophy |
| 60% | 69.5 kg | More than 12 | Warm-up, technique |
The NSCA chart works both ways. Its own example: if you squat 160 lb for 8 reps, 160 is 80% of an estimated 200 lb 1RM. Our six-formula average for the same set is 199.4 lb, within 1% of the chart.
Estimating your bench press, squat and deadlift
The same formulas work for any barbell lift. Here are three example sets:
| Lift | Set completed | Epley | Brzycki | Six-formula average |
|---|---|---|---|---|
| Bench press | 60 kg × 10 | 80 kg | 80 kg | 78.3 kg |
| Squat | 140 kg × 3 | 154 kg | 148.2 kg | 153.5 kg |
| Deadlift | 180 kg × 2 | 192 kg | 185.1 kg | 191.5 kg |
Notice how Epley and Brzycki agree at 10 reps but drift apart at low reps. For dumbbell presses, the leg press and other machines, treat the result as rougher, since most studies behind these formulas tested barbell lifts such as the bench press and squat.
Getting a reliable estimate
- Pick the right set. Sets of 3 to 8 reps taken close to failure give the most consistent estimates. Very high-rep sets measure endurance as much as strength.
- Use the same lift. A bench press 1RM does not predict your squat. Estimate each lift separately, and expect bigger errors on the deadlift and on machine exercises.
- Keep form strict. A rep with a bounce, a half range of motion or help from a spotter inflates the estimate.
- Retest every few weeks. Strength changes, so update your numbers at the start of each training block.
In a 1997 study, LeSuer and colleagues checked seven prediction equations against real 1RM tests in untrained college students on the bench press, squat and deadlift. Predicted and actual values were closely related, but the equations underestimated the deadlift, which is why lift-specific caution matters.
Using your 1RM in training
Most programs prescribe loads as a percentage of 1RM. Heavy sets of 1 to 6 reps at 85% or more build maximal strength, moderate sets of 6 to 12 reps at about 67% to 85% suit muscle growth, and lighter sets of 12 or more reps build muscular endurance. Pair your lifting with enough protein and energy: the protein calculator and TDEE calculator help you set daily targets, and the calories burned calculator estimates the energy cost of a session.
One Rep Max Calculator: frequently asked questions
What is a one-rep max?
Your one-rep max (1RM) is the most weight you can lift for a single repetition of an exercise with proper form. Coaches use it to set training loads as a percentage, such as 5 sets of 5 reps at 80% of 1RM.
How do I calculate my one-rep max?
Lift a weight for as many good reps as you can (ideally 2 to 10), then plug it into a formula. With 100 kg for 5 reps, Epley gives 100 × (1 + 5 ÷ 30) = 116.7 kg and Brzycki gives 100 × 36 ÷ 32 = 112.5 kg. The average of six formulas is 115.8 kg.
How do I calculate my bench press one-rep max?
Use the same method with a bench press set. A bench of 225 lb for 5 reps gives an estimated 1RM of 262.5 lb by Epley, 253.1 lb by Brzycki and 260.5 lb as the six-formula average.
Which one-rep max formula is the most accurate?
No formula wins for every lift and every person. Epley and Brzycki are the most widely used and agree exactly at 10 reps: 100 lb for 10 reps gives 133.3 lb with both. At lower reps Epley reads higher, for example 120 lb versus 116.1 lb at 6 reps.
How many reps can I do at 80% of my 1RM?
About 8, according to the NSCA training load chart. The chart also lists about 10 reps at 75%, 6 reps at 85% and 4 reps at 90%. Individuals vary, especially on lower-body lifts.
Why are estimates less accurate above 10 reps?
High-rep sets test muscular endurance as well as strength, and people differ a lot in how many reps they can do at a given percentage. The formulas also start to disagree: 80 kg for 12 reps gives anywhere from 102.6 kg (Lombardi) to 115.2 kg (Brzycki).
Is it safe to test a true one-rep max?
Testing a true 1RM is generally considered safe for trained lifters with good technique, a thorough warm-up and a spotter or safety bars. Beginners usually get a safer and good-enough number from a 3 to 8 rep set and a formula.
How we checked this page: every figure in the examples and FAQs above is produced by this calculator and verified by automated tests against known answers, and the rules and rates come from the sources below. Last updated . Spotted a problem? Tell us.