1RM Calculator
Your one rep max from a set of reps, in lb or kg. The average of the Epley and Brzycki formulas, with a percentage chart from 50 to 100%.
Your estimated 1RM
258 lb
Average of the Epley and Brzycki formulas- Epley 263 lb
- Brzycki 253 lb
- 90% of 1RM 232 lb
- 75% of 1RM 193 lb
What your 1RM means
Your one rep max (1RM) is the heaviest weight you could lift once with good form. Testing it directly is hard and risky without a spotter, so this calculator estimates it from a lighter set done close to failure.
Use it to set training weights, not as a record. The fewer reps in your set, the better the estimate: both formulas were built for low reps, and they spread apart as the reps climb. A 2014 study found that people with different training backgrounds can do very different numbers of reps at the same percentage of their max.
- Use a recent, honest set: the last rep should have been hard.
- Each lift has its own 1RM. Run the calculator once for bench press, once for squat, once for deadlift.
- Test heavy singles with a spotter or safety bars, never alone.
The formulas: Epley and Brzycki
Epley: 1RM = w × (1 + r / 30)
Brzycki: 1RM = w × 36 / (37 − r)
Result = (Epley + Brzycki) / 2
w = weight lifted, r = reps (1 to 12)
At r = 1, 1RM = wEpley's formula comes from Boyd Epley's 1985 Poundage Chart (Body Enterprises, Lincoln, Nebraska), which has no online copy; Brzycki's was published in 1993 in the Journal of Physical Education, Recreation and Dance. Both are unit-free: the result comes out in the unit you typed. The two give the same answer at 10 reps; under 10, Epley is the higher one, over 10, Brzycki is.
Source without a link: Epley B. Poundage Chart. In: Boyd Epley Workout. Lincoln, NE: Body Enterprises; 1985.
Worked example in pounds
225 lb for 5 reps:
- Epley = 225 × (1 + 5 / 30) = 262.5 lb
- Brzycki = 225 × 36 / (37 − 5) = 253.1 lb
- 1RM = (262.5 + 253.1) / 2 = 258 lb
Worked example in kilograms
80 kg for 8 reps:
- Epley = 80 × (1 + 8 / 30) = 101.3 kg
- Brzycki = 80 × 36 / (37 − 8) = 99.3 kg
- 1RM = (101.3 + 99.3) / 2 = 100.5 kg
Your weights from 50 to 100%
From the 1RM in the calculator above, rounded to the nearest 1 lb or 0.5 kg. Want a version to print? See the 1RM percentage chart.
| % of 1RM | Weight (lb) |
|---|---|
| 100% | 258 |
| 95% | 245 |
| 90% | 232 |
| 85% | 219 |
| 80% | 206 |
| 75% | 193 |
| 70% | 180 |
| 65% | 168 |
| 60% | 155 |
| 55% | 142 |
| 50% | 129 |
Variants of this calculator
The same formula with defaults, tables and notes set up for one use.
Frequently asked questions
How do I calculate my one rep max?
Do a set of 1 to 12 reps close to failure, then enter the weight and the reps. The calculator applies two formulas, Epley (weight × (1 + reps / 30)) and Brzycki (weight × 36 / (37 − reps)), and shows their average. For 225 lb × 5 reps, that is 258 lb.
Does the formula change for bench press, squat or deadlift?
No. Both formulas use only the weight and the number of reps, so the same calculator works for bench press, squat, deadlift or any other lift. A 1997 study by LeSuer and colleagues tested 1RM prediction equations on exactly these three lifts; see the sources below.
How accurate is a 1RM calculator?
It is an estimate, best with a low number of reps. Neither the Epley chart nor the Brzycki equation was published with the data behind it, as a 2014 paper points out, and that paper found trained people differ a lot in how many reps they can do at a given percentage: endurance athletes did 19.8 reps at 80% of their max, weightlifters 11.8. Treat the result as a starting point for your training weights.
How many reps should I use?
Use a set of about 3 to 6 reps for the closest estimate; the two formulas agree best there and drift apart as reps go up. The calculator accepts 1 to 12. At 1 rep, your 1RM is simply the weight lifted.
What percentage of my 1RM should I train at?
That depends on your program and goal, which is beyond what this calculator can tell you. What it does give you is the weight at each percentage from 50 to 100%, so you can follow a program written in percentages. For a printable version, see the 1RM percentage chart.
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Medical disclaimer
This calculator gives an estimate, not medical advice. Equations predict the average of a group; your own needs can sit 10% or more above or below. It is built for healthy adults. If you are pregnant or breastfeeding, under 18, living with a medical condition such as diabetes, kidney disease or an eating disorder, or taking medication that affects appetite or weight, ask your doctor or a registered dietitian before acting on these numbers.
Sources
- Brzycki M. Strength testing: predicting a one-rep max from reps-to-fatigue. J Phys Educ Recreat Dance. 1993;64(1):88-90. DOI: 10.1080/07303084.1993.10606684
- LeSuer DA, McCormick JH, Mayhew JL, Wasserstein RL, Arnold MD. The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. J Strength Cond Res. 1997;11(4):211-213. DOI: 10.1519/00124278-199711000-00001
- Richens B, Cleather DJ. The relationship between the number of repetitions performed at given intensities is different in endurance and strength trained athletes. Biol Sport. 2014;31(2):157-161. DOI: 10.5604/20831862.1099047