Epley Formula vs Brzycki: Which 1RM Formula Should You Use?

By the One Rep Max Calculator team · Published October 24, 2026 · Facts checked against the sources listed below · About us

Safety note. These numbers are estimates for healthy adults. They are not medical advice. Max lifts carry real risk. Warm up, use a spotter or safety bars, and stop if you feel pain. If you have a health condition, an injury or are new to lifting, talk to a doctor or a certified coach first. The Physical Activity Guidelines for Americans suggest muscle strengthening at least 2 days a week.

On Reddit’s r/weightroom and r/GarageStrength, lifters keep asking the same thing. Which 1RM formula is best? Why does my app give a different max than my friend’s app? Most of the time, the answer is that the apps use different formulas. The two you will see most are Epley and Brzycki. This guide shows how each one works, where they differ, and which to use.

The short answer

The Epley formula is weight x (1 + reps / 30). The Brzycki formula is weight x 36 / (37 minus reps). They give almost the same answer for 2 to 5 reps. From 6 to 9 reps, Epley gives a bit more. At 10 reps they match. Pick one, and use it every time.

The Epley formula

Epley adds one thirtieth of the weight for every rep you did.

1RM = w x (1 + r / 30)

Here, w is the weight and r is the reps. Some sources write it as w x (1 + 0.0333 x r). That is the same thing.

Example: 100 kg for 6 reps.

100 x (1 + 6 / 30) = 100 x 1.2 = 120 kg.

Epley is a straight line. Each extra rep adds the same amount to your max, about 3.3% of the weight lifted.

The Brzycki formula

Brzycki divides by a number that shrinks as reps go up.

1RM = w x 36 / (37 minus r)

It is also written as 100 x w / (102.78 minus 2.78 x r). That is the same math, rounded.

Example: 100 kg for 6 reps.

100 x 36 / (37 minus 6) = 100 x 36 / 31 = 116.1 kg.

Brzycki is a curve. At low reps it adds less than Epley. At high reps it adds more, and it grows fast once you go past 10.

Side by side

Here is what each formula gives for 100 kg at different reps.

Reps	Epley	Brzycki	Gap
1	100	100	0
2	106.7	102.9	3.8
3	110.0	105.9	4.1
5	116.7	112.5	4.2
6	120.0	116.1	3.9
8	126.7	124.1	2.6
10	133.3	133.3	0
12	140.0	144.0	minus 4.0

A note on 1 rep. Plain Epley math gives 103.3 for a single. Most tools, including ours, just return the weight you lifted for 1 rep. You already lifted it, so that is your max.

The gap between the two is never more than about 4%. For most people, that is about the same as the change from a good day to a bad day.

Where the formulas come from

Both formulas were built by watching groups of lifters. Each group did a true max and a set of reps. The authors then drew a line or curve through the data.

That means each formula fits the group it came from. If you are built like that group, it may fit you well. If not, it may be a bit off.

What the research says

The best known test of these formulas is a 1997 study by LeSuer and others. It checked seven formulas, Epley and Brzycki among them, with 67 college students new to lifting (LeSuer and others, 1997).

The study had each student do a real max and a set to failure on three lifts. It found:

All seven formulas tracked real maxes closely. The correlations were above 0.95.
On the bench press, only 2 of the 7 formulas had an average error close to zero.
On the squat, only 1 of the 7 did.
On the deadlift, every formula guessed too low.

So neither Epley nor Brzycki is perfect. Both are good at ranking lifters, and both can miss a person’s true max by a few pounds.

A 2006 study adds another point. It found a 5 rep set gave the best guess of a true max. It advised not to use more than 10 reps in these kinds of formulas (Reynolds and others, 2006). That fits the table above. At 5 reps, the two formulas are only about 4% apart. At 12 reps, the gap starts to grow the other way.

Other formulas you will see

Epley and Brzycki are not the only choices. The 1997 study also tested these:

Lander: 100 x w / (101.3 minus 2.67123 x r). Very close to Brzycki.
Lombardi: w x r to the power of 0.1. Gives higher numbers at low reps.
Mayhew: uses an exponential curve. Often one of the higher results.
O’Conner: w x (1 + 0.025 x r). The lowest of the group, along with Brzycki at low reps.
Wathan: also uses an exponential curve, close to Epley at most reps.

Our one rep max calculator shows all seven next to each other, plus the average.

How the NSCA chart compares

The NSCA training load chart is not a formula, but it does the same job. It lists the percent of your max you can lift for a given number of reps (NSCA).

At 5 reps, the chart says 87%. That gives 100 / 0.87 = 114.9 kg, right between Epley and Brzycki. At 10 reps, it says 75%, which gives 133.3 kg, the same as both formulas.

When three methods land this close, you can trust the range.

So which should you use?

Here is a simple way to choose.

Use Epley if you want a single, easy formula you can do in your head. It is a little more generous for sets of 6 to 9 reps.

Use Brzycki if you mostly test with low reps, like 2 to 5. It gives slightly lower, more careful numbers at that range.

Use the average if you are not sure. It smooths out the quirks of any one formula.

Most of all, be consistent. If you use Epley in January and Brzycki in March, you could see a fake jump or drop of 4%. That can hide real progress.

Tips for a better estimate

Use a set of 3 to 6 hard reps.
Count only clean reps with full range of motion.
Do the set early in the workout, when you are fresh.
For the deadlift, expect the result to be low. Read more on our deadlift calculator page.
If you stopped short of failure, add the reps you had left. Our RPE chart guide shows how.

Bottom line

Epley and Brzycki give close answers for normal rep counts. Epley is a straight line and a bit more generous below 10 reps. Brzycki is a curve and a bit more careful at low reps. The research says both are good, and neither is exact. Choose one, use low reps, and stick with it. For a full walk through, see our guide on how to calculate your 1RM.

Tools for this guide

FAQ

What is the Epley formula?

The Epley formula estimates your one rep max as weight times 1 plus reps divided by 30. So 100 kg for 6 reps gives 100 x 1.2 = 120 kg. It is one of the most widely used 1RM formulas.

Is Epley or Brzycki more accurate?

Neither wins in every case. They agree closely at low reps. Epley gives higher numbers as reps go up to about 10. In a 1997 study of seven formulas, none was right on average for all three big lifts.

Why do the two formulas match at 10 reps?

At 10 reps, Epley gives weight x 1.333 and Brzycki gives weight x 36 / 27, which is also 1.333. Below 10 reps Epley is higher. Above 10 reps Brzycki climbs faster.

Which formula do apps use?

Many apps use Epley or Brzycki, and some let you choose. Check the settings of your app. Whatever it uses, keep the same one over time so your numbers stay comparable.