The answer at a glance
Formula
1 + reps/30
Multiply the weight you lifted by this.
100 kg for 5 reps
116.7kg
Estimated 1RM from the example.
Built on
10 or fewerreps
Sets taken to fatigue. More reps, rougher result.
Meets Brzycki at
10reps
Epley is higher below that and lower above it.
Key Takeaways
- The Epley formula is 1RM = weight × (1 + reps ÷ 30)[2]. For 100 kg for 5 reps that is 116.7 kg, and for 200 lb for 8 reps it is 253.3 lb.
- LeSuer and colleagues cite it to a 1985 poundage chart, not to a study[1]. They printed it as 1 + 0.0333 × reps and tested it against six other equations[2].
- It was built on sets of 10 or fewer reps taken to fatigue[2]. The calculator warns above that, and when a set stopped with reps left.
- In LeSuer's untrained students it read low on all three lifts: by 2.2 lb on the bench press, 6.7 lb on the squat and 24.0 lb on the deadlift[2].
- No source here gives one error figure for it. The Australian Institute of Sport goes further: it says not to calculate a 1RM from reps, cites ±10% variability, and asks you to log the weight and reps instead[6].
What Is the Epley Formula?
A one-line rule that turns a hard set into an estimated one rep max.
The formula comes from a poundage chart in the Boyd Epley Workout, published by Body Enterprises in Lincoln, Nebraska, in 1985[1]. The chart itself wasn't opened for this page. The citation comes from the reference list of LeSuer and colleagues[2].
You'll see some sites call it a study or say it's been validated. None of the papers cited here use that wording. LeSuer's group lists it as one of seven equations and tests them all together[2].
The original was a chart, and the algebra is how it's quoted today. LeSuer prints it as 1 + 0.0333 × reps, while this page uses reps ÷ 30. The two differ by under 0.1% for 1 to 15 reps (worked out here).
The Epley Formula and How to Use It
Multiply the weight you lifted by 1 plus the reps divided by 30.
Enter the total weight on the bar and the reps you completed to failure. The unit comes out the same as it went in, so 100 kg gives kilograms and 100 lb gives pounds.
1RM from a set
weight × (1 + reps ÷ 30)
Weight for a rep target
1RM ÷ (1 + reps ÷ 30)
Reps at a weight
30 × (1RM ÷ weight − 1)
One rep
1RM = the weight lifted
100 × (1 + 5 ÷ 30)
= 100 × 1.17
200 × (1 + 8 ÷ 30)
= 200 × 1.27
Two more examples, run through the same function the calculator uses. A 225 lb squat for 8 reps gives 285.0 lb, and 80 kg for 10 reps gives 106.7 kg.
Why one rep returns the weight
Written literally, the equation adds 1/30, or 3.3%, to a single. A single is already a max as lifted, so the calculator returns the weight you entered and says so.
Epley Formula Chart: Reps and Percent of 1RM
At 5 reps the equation puts your set at 85.7% of your max, at 8 reps 78.9%, and at 10 reps 75.0%.
The chart works for any weight, because the equation scales. Multiply your 1RM by the percent, or divide a set's weight by it, to move between them.
| Reps | Epley multiplier | Epley % of 1RM | Brzycki % of 1RM |
|---|---|---|---|
| 1 | 1.00 | 100.0% | 100.0% |
| 2 | 1.07 | 93.8% | 97.2% |
| 3 | 1.10 | 90.9% | 94.4% |
| 4 | 1.13 | 88.2% | 91.7% |
| 5 | 1.17 | 85.7% | 88.9% |
| 6 | 1.20 | 83.3% | 86.1% |
| 7 | 1.23 | 81.1% | 83.3% |
| 8 | 1.27 | 78.9% | 80.5% |
| 9 | 1.30 | 76.9% | 77.8% |
| 10 | 1.33 | 75.0% | 75.0% |
| 11 | 1.37 | 73.2% | 72.2% |
| 12 | 1.40 | 71.4% | 69.4% |
| 13 | 1.43 | 69.8% | 66.6% |
| 14 | 1.47 | 68.2% | 63.9% |
| 15 | 1.50 | 66.7% | 61.1% |
Epley vs Brzycki
The two agree at 10 reps. Below that Epley gives the higher max, and above it Brzycki does.
Epley adds the same amount for every rep. Brzycki's equation[5] divides by a number that shrinks as reps rise, so each extra rep adds a little more than the last (worked out here). The two meet at 10 reps.
Which one lands closer depends on the reps you start from. In DiStasio's squat data, Epley was closer from 3-rep sets (+2.7 kg against −4.8 kg for Brzycki) and Brzycki from 5-rep sets (−3.1 kg against +4.0 kg)[3]. That is one small group of young men, so treat it as an example.
| Reps | Epley (kg) | Brzycki (kg) | Difference (kg) |
|---|---|---|---|
| 3 | 110.0 | 105.9 | +4.1 |
| 5 | 116.7 | 112.5 | +4.2 |
| 8 | 126.7 | 124.2 | +2.5 |
| 10 | 133.3 | 133.4 | −0.0 |
| 12 | 140.0 | 144.1 | −4.1 |
For the sets most people use to estimate a max, 3 to 8 reps, Epley gives the higher number, by a few kilograms at 100 kg. That's why the calculator shows both: you see the spread, not just one figure.
For all seven equations from LeSuer's table, and a recommended blend, use the One Rep Max Calculator.
How Accurate Is the Epley Formula?
It depends on the lift, the lifter and the rep count, and no source here gives a single error figure.
LeSuer and colleagues tested it on 67 untrained college students, 40 men and 27 women[2]. Some skipped the squat or deadlift, so those lifts have fewer people. All predictions correlated strongly with the measured 1RM, but the averages came out low on every lift[2].
| Lift | Epley estimate (lb) | Measured 1RM (lb) | Gap, lb (%) |
|---|---|---|---|
| Bench press | 135.1 | 137.3 | −2.2 (1.6%) |
| Squat | 201.3 | 208.0 | −6.7 (3.2%) |
| Deadlift | 212.5 | 236.5 | −24.0 (10.1%) |
A graduate paper tested the squat in Division I football players aged 18 to 23[3]. From 3 reps, Epley averaged 2.7 kg above the measured 1RM and the difference was not significant. From 5 reps it averaged 4.0 kg above, and that difference was significant (p = 0.033)[3].
That paper is a master's research paper, not a journal article. A conference abstract on Division II football players found Lander and Polson tended to be most accurate, but not by a practical margin[4]. It calls all the equations accurate within the 4 to 5 kg change usually accepted for this test[4].
What the sources point to
What they do not show
The samples were untrained students and young football players. They say little about older lifters, women who train, or lifts other than the bench press, squat and deadlift.
The Australian Institute of Sport's current protocols (version 3.0, April 2025) are blunter. They say predictive equations should not be used to calculate a 1RM, because results shift with the muscle group, exercise and training level, with ±10% variability[6]. For test records they ask for the actual weight and reps[6].
Using Your Epley Result
Treat it as a planning number, and test a heavy set now and then to see how close it is.
The calculator turns the estimate into loads by rep count and by percent of your max, rounded to the plates you have. It does not tell you which percent to train at, because none of the sources here gives goal-based percentage bands.
If your set stopped with reps left, the formula reads low. The RPE to 1RM calculator is built for that case, and the RIR to RPE calculator converts between the two scales.
To start from a specific rep max, there are the 3 rep max, 5 rep max and 10 rep max calculators. For loads you will actually lift today, the warm-up calculator builds the ramp.
Not Covered
These are outside what this calculator can say, because no cited source supports a number for them.
Training percent by goal
No cited source gives percent bands for strength, size or endurance, so the tables show loads by percent without saying which to use.
Strength levels and standards
Rating a lift as beginner, intermediate or advanced needs a sourced standard. None is used here.
Lifts other than the big three
LeSuer tested the bench press, squat and deadlift. For any other lift the page says there is no accuracy data.
Frequently Asked Questions
Sources & References
- Poundage chart (original not opened; cited as reference 5 in LeSuer et al. 1997). Epley B. Boyd Epley Workout. Lincoln, NE: Body Enterprises (1985)
- The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. LeSuer DA, McCormick JH, Mayhew JL, Wasserstein RL, Arnold MD. Journal of Strength and Conditioning Research 11(4):211-213 (1997)
- Validation of the Brzycki and Epley Equations for the 1 Repetition Maximum Back Squat Test in Division I College Football Players (master's research paper, not a journal article). DiStasio TJ. Southern Illinois University Carbondale, Research Papers, Graduate School (2014)
- Validity of Predicting One Repetition Maximum Strength from Sub-maximal Repetitions to Fatigue (conference abstract: the abstract was read, the full text was not opened). Hendrickson N, et al.. Medicine & Science in Sports & Exercise 40(5):S417 (2008)
- Strength Testing: Predicting a One-Rep Max from Reps-to-Fatigue. Brzycki M. Journal of Physical Education, Recreation & Dance 64(1):88-90 (1993)
- National Protocols for the Assessment of Strength and Power, Version 3.0 (April 2025). Australian Institute of Sport and the National Institute Network. Australian Sports Commission (2022)
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Disclaimer: This tool is for informational and personal journaling purposes only. Results are estimates based on published formulas and may vary based on individual factors such as genetics, training history, and measurement technique.