One Rep Max CalculatorHow to calculate your one rep max
Do a set with good form until you could not do another rep. Note the weight and the reps. Put them into a formula. With Epley, multiply the weight by 1 plus reps divided by 30. So 225 lb for 5 reps gives an estimated max of 262.5 lb.
Here is the same set with two formulas, worked by hand:
- Epley: 225 x (1 + 5 / 30) = 225 x 1.1667 = 262.5 lb.
- Brzycki: 225 x 36 / (37 minus 5) = 225 x 36 / 32 = 253.1 lb.
- The two results are about 9 lb apart. That gap is normal. It is why the tool shows all seven side by side.
The sample set of 225 lb for 5 reps loads in the tool. Change it and the numbers update as you type.
The 7 formulas in this tool
All seven come from the table in a 1997 study by LeSuer and others in the Journal of Strength and Conditioning Research. In each one, w is the weight lifted and r is the reps.
| Formula | Estimated 1RM |
|---|---|
| Epley | w x (1 + 0.0333 x r) |
| Brzycki | 100 x w / (102.78 minus 2.78 x r) |
| Lander | 100 x w / (101.3 minus 2.67123 x r) |
| Lombardi | w x r to the power of 0.1 |
| Mayhew | 100 x w / (52.2 + 41.9 x e to the power of (minus 0.055 x r)) |
| O'Conner | w x (1 + 0.025 x r) |
| Wathan | 100 x w / (48.8 + 53.8 x e to the power of (minus 0.075 x r)) |
Brzycki is often written as w x 36 / (37 minus r). It is the same math. For a single rep, the tool returns the weight you lifted, since that already is your max.
Which 1RM formula is most accurate?
No single formula wins for every lift. In the 1997 study, all seven tracked real maxes closely, with correlations above 0.95. Still, most were a bit off on average for the bench press and squat, and every one of them guessed too low for the deadlift. Use the average when you are not sure.
The study tested 67 college students who were new to lifting (LeSuer and others, 1997). For the bench press, only 2 of the 7 formulas had an average error close to zero. For the squat, only 1 did. A later study of 70 adults found that a 5 rep max gave the best guess, and it said not to use more than 10 reps (Reynolds and others, 2006).
So the rule of thumb is simple. Use a hard set of 3 to 6 reps. Use the same formula each time. Then your progress is easy to track, even if the exact number is a little off.
1RM percentage chart
The National Strength and Conditioning Association (NSCA) publishes a training load chart. It shows how many reps most people can do at each percent of their max. The tool uses these values for the reps column.
| Max reps | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 12 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| % of 1RM | 100 | 95 | 93 | 90 | 87 | 85 | 83 | 80 | 77 | 75 | 70 |
The chart works both ways. The NSCA example says 8 reps at 160 lb points to a max of about 200 lb. It also says that with a 200 lb max, you should be able to do 10 reps at 150 lb, which is 75%.
How to use your max to plan training
The American College of Sports Medicine (ACSM) gives load ranges by training level in its position stand on progression (ACSM, 2009):
- New lifters: loads you can lift for 8 to 12 reps, 2 to 3 days a week.
- Intermediate and advanced lifters: a wider range of 1 to 12 rep loads over time, with more focus on heavy 1 to 6 rep loads. Rest 3 to 5 minutes between heavy sets.
- When to add weight: once you can do 1 or 2 reps more than your goal, add 2% to 10% to the bar.
Use the percent chart in the tool to turn these ranges into real weights. For example, with a 262.5 lb max, 80% is about 210 lb, which most people can lift for about 8 reps.
Should you test a true max?
You do not have to. The Human Performance Resources center at the Uniformed Services University says a multiple rep test is a good choice if you train alone without a spotter (HPRC). If you do test, it lists the NSCA steps:
- Warm up with a light load you can lift 5 to 10 times. Rest 1 minute.
- Do a load you can lift 3 to 5 times. Rest 2 minutes.
- Do a near max load for 2 to 3 reps. Rest 2 to 4 minutes.
- Add weight and try 1 rep. Add 5% to 10% for upper body lifts, or 10% to 20% for lower body lifts.
- Keep going up or down until you find the most you can lift once with good form.
Always use a spotter or safety bars on the bench press and squat.
More tools
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FAQ
What is a one rep max?
Your one rep max, or 1RM, is the most weight you can lift for one full rep with good form. It is not the most you can grind out with a sloppy rep. Coaches use it to set training loads as a percent of your max.
Which 1RM formula should I use?
Epley and Brzycki are the most common, and they agree closely for sets of 2 to 6 reps. In a 1997 study of seven formulas, all of them tracked real maxes well, but most were a little off on average. Pick one formula and stick with it so your numbers stay comparable.
How many reps give the best estimate?
Lower reps give a better guess. A 2006 study found a 5 rep max predicted the true max best, and it said not to use more than 10 reps. Sets of 3 to 6 hard reps work well in this tool.
Can I use kg and lb?
Yes. Pick kg or lb in the Unit box. If you switch units, the tool converts the weight you typed for you, using 1 lb = 0.45359237 kg.
Is it safe to test my true max?
It can be, for healthy lifters with good form and a spotter or safety bars. Beginners do not need to test a true max. A hard set of 3 to 5 reps and an estimate is a lower risk way to get a useful number.
Why does my estimate differ from my real max?
Formulas are averages from groups of lifters. Your own result depends on how fresh you are, your technique, the lift and your muscle fiber mix. Studies show all seven formulas tend to underestimate the deadlift.
References
- LeSuer DA et al. The accuracy of prediction equations for estimating 1RM performance in the bench press, squat, and deadlift. J Strength Cond Res. 1997;11(4):211-213
- Reynolds JM, Gordon TJ, Robergs RA. Prediction of one repetition maximum strength from multiple repetition maximum testing and anthropometry. J Strength Cond Res. 2006 (PubMed)
- Training Load Chart, National Strength and Conditioning Association (NSCA)
- American College of Sports Medicine position stand. Progression models in resistance training for healthy adults. Med Sci Sports Exerc. 2009 (PubMed)
- What is a one rep max? Human Performance Resources by CHAMP (HPRC), Uniformed Services University
- Top 10 Things to Know About the Second Edition of the Physical Activity Guidelines for Americans, U.S. Department of Health and Human Services