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The short answer
- For sets of 2 to 9 reps, Epley gives a slightly higher estimate than Brzycki, by up to about 4%.
- At 10 reps they give exactly the same answer.
- Above 10 reps, Brzycki climbs faster, and past about 15 reps it runs far higher than Epley.
- Neither has been shown to be the most accurate for every lifter and every lift. Pick one, use it every time, and stay in the 2 to 10 rep range.
Try both on your own numbers with the one rep max calculator. Open More options to switch the formula.
The Epley formula (and a 225 lb × 10 walkthrough)
1RM = weight × (1 + reps ÷ 30)
The Epley formula comes from strength coach Boyd Epley's work at the University of Nebraska in the 1980s. It adds a fixed 3.33% of the weight for each rep. That makes it a straight line: every extra rep adds the same amount to your estimated max.
Bench press, 225 lb for 10 reps:
- Divide reps by 30: 10 ÷ 30 = 0.333
- Add 1: 1.333
- Multiply by the weight: 225 × 1.333 = 300 lb
The Brzycki formula (same example, both give 300 lb)
1RM = weight × 36 ÷ (37 − reps)
Matt Brzycki published this formula in 1993. Instead of a straight line, it is a curve: the reps sit in the bottom part of a fraction, so each extra rep adds a little more than the one before.
Same set, 225 lb for 10 reps:
- Subtract reps from 37: 37 − 10 = 27
- Multiply the weight by 36: 225 × 36 = 8,100
- Divide: 8,100 ÷ 27 = 300 lb
Both formulas land on exactly 300 lb. That is not a coincidence: at 10 reps, 1 + 10 ÷ 30 and 36 ÷ 27 are both exactly 4/3. In kilograms, 100 kg for 10 reps gives 133.3 kg with both.
Where the two formulas agree, and where they differ
Here is every common rep count for a 225 lb set, worked out with both formulas.
| Reps | Epley | Brzycki | Difference |
|---|---|---|---|
| 2 | 240 lb | 231.4 lb | 8.6 lb |
| 3 | 247.5 lb | 238.2 lb | 9.3 lb |
| 4 | 255 lb | 245.5 lb | 9.5 lb |
| 5 | 262.5 lb | 253.1 lb | 9.4 lb |
| 6 | 270 lb | 261.3 lb | 8.7 lb |
| 8 | 285 lb | 279.3 lb | 5.7 lb |
| 10 | 300 lb | 300 lb | 0 |
| 12 | 315 lb | 324 lb | 9 lb |
| 15 | 337.5 lb | 368.2 lb | 30.7 lb |
| 20 | 375 lb | 476.5 lb | 101.5 lb |
Three things stand out:
- Below 10 reps the gap is small. Under 10 lb on a 225 lb set, or no more than about 4%. For most training, that difference won't change what you load on the bar.
- At 10 reps they meet. That is the one point where they agree exactly.
- Above 12 reps they split apart. At 20 reps Brzycki predicts a 476.5 lb max from a 225 lb set, more than double the weight, which is not realistic for most lifters. The formula also breaks completely at 37 reps, where it would divide by zero. Long sets are a bad input for any formula, but especially for Brzycki.
The same pattern in kilograms, for 100 kg:
| Reps | Epley | Brzycki |
|---|---|---|
| 3 | 110 kg | 105.9 kg |
| 5 | 116.7 kg | 112.5 kg |
| 8 | 126.7 kg | 124.1 kg |
| 10 | 133.3 kg | 133.3 kg |
Which formula is better at 3, 5 or 10 reps?
3 reps: Both are close to the weight lifted, so both give a reasonable estimate. Brzycki is the more cautious of the two. If you want training weights that err on the safe side, Brzycki is a good choice for heavy triples.
5 reps: The most common set for estimating a max. The two differ by about 9 lb on a 225 lb set (262.5 vs 253.1 lb). If you have tested your max before, check which one landed closer for you, and keep using that one.
10 reps: It doesn't matter: they give the same answer. But a 10-rep set depends more on endurance than a 3- or 5-rep set, so either estimate is a little less certain than one from a heavier set.
12+ reps: Use Epley if you have to, and treat the answer as rough. Better still, do a heavier set. See are 1RM calculators accurate? for why high-rep sets give shaky estimates.
Other formulas in brief
RepMaxLab runs five more formulas next to Epley and Brzycki. For a 225 lb set of 5 reps they give:
| Formula | Equation | Estimated 1RM |
|---|---|---|
| Epley | w × (1 + r ÷ 30) | 262.5 lb |
| Brzycki | w × 36 ÷ (37 − r) | 253.1 lb |
| Lander | 100 × w ÷ (101.3 − 2.67123 × r) | 255.8 lb |
| Lombardi | w × r0.10 | 264.3 lb |
| Mayhew | 100 × w ÷ (52.2 + 41.9 × e−0.055 × r) | 267.8 lb |
| O'Conner | w × (1 + 0.025 × r) | 253.1 lb |
| Wathan | 100 × w ÷ (48.8 + 53.8 × e−0.075 × r) | 262.3 lb |
- Lander tracks Brzycki closely across the range.
- O'Conner is like Epley with a smaller step per rep, so it is cautious.
- Lombardi runs high on short sets and low on long ones.
- Mayhew and Wathan are curves that flatten as reps rise, so they handle longer sets more gently.
The full explanation of each one is on the one rep max calculator page.
What RepMaxLab uses, and why
The calculators on this site use Epley by default. It is simple, widely used in lifting apps and programs, and it behaves sensibly as reps go up: it never explodes the way Brzycki does on long sets. You can switch to Brzycki or any of the other formulas, or to the average of all seven, under More options. The average is a good pick if you would rather not bet on one equation.
Whatever you choose, consistency matters more than the formula. If you always use Epley, your estimates are comparable from month to month, and that is what shows real progress.
Want to do the math by hand? How to calculate your 1RM has a multiplier table for both formulas. Need a rep max other than one? The 3 rep max calculator runs the formulas in reverse.
1RM formula FAQ
Is Epley or Brzycki more accurate?
Neither wins for every lifter and lift. Both are reasonable for sets of 2 to 10 reps. Epley reads a few percent higher below 10 reps. Brzycki climbs much faster above 12 reps, so Epley is the safer choice for longer sets.
Why do Epley and Brzycki give the same answer at 10 reps?
At 10 reps, the Epley multiplier (1 + 10 ÷ 30) and the Brzycki multiplier (36 ÷ 27) are both exactly 1.333. So 225 lb for 10 reps gives 300 lb with both.
What is the Epley formula for 1 rep max?
1RM = weight × (1 + reps ÷ 30). For 185 lb for 6 reps: 185 × 1.2 = 222 lb.
What is the Brzycki formula for 1 rep max?
1RM = weight × 36 ÷ (37 − reps). For 100 kg for 5 reps: 3,600 ÷ 32 = 112.5 kg.
Which formula does RepMaxLab use?
Epley by default. You can switch to Brzycki, five other formulas or the average of all seven under More options in any calculator.