Enter the weight you lifted and the reps you did, and get your estimated one-rep max
from both the Epley and Brzycki formulas, plus their average. You'll also get a full
percentage-of-1RM table — the estimated load at every training percentage and the
reps it roughly corresponds to — so you never have to test a true max to program
your lifts.
Epley, Brzycki & average·Full training-percentage table·Pounds or kilograms
Read this first
A one-rep max from a formula is an estimate, not a measurement. It's most accurate
when your set is five reps or fewer and taken close to failure, and it gets unreliable above
roughly twelve to fifteen reps. If you do attempt an actual heavy single, warm up thoroughly,
use clean form, and set up a spotter or safety bars first. This page is general information,
not training or medical advice — train within your ability and progress gradually.
Pick your unit, enter the weight you lifted and the number of reps you completed, and you'll get the Epley and Brzycki estimates, their average, and a percentage table built from that average.
The weight on the bar for your work set, in pounds.
Whole reps taken close to failure. 1–5 is most accurate; above 12–15 is unreliable.
Epley estimate (weight × (1 + reps/30))
Brzycki estimate (weight × 36 / (37 − reps))
Average of the two
Training loads at each % of your 1RM
% of 1RM
Estimated loadbased on average 1RM
Roughlyreps at this load
The math, honestly
How the estimate is figured
Both formulas turn a set of reps into a projected single. Epley is
weight × (1 + reps/30) — it adds a fixed slice of the weight for
every rep past the first, so its line keeps climbing steadily. Brzycki is
weight × 36 / (37 − reps) — it divides by a shrinking
denominator, so its estimate rises faster as reps grow and is undefined at 37
reps, where the denominator hits zero. At one rep both formulas
simply return the weight you lifted.
Why we show both, plus the average: the two equations agree closely at
low reps and drift apart as reps climb. For a set of five they differ by only a few
percent; for a set of fifteen the gap is large. Reporting both and their average is more
honest than a single precise-looking number, because your true max almost certainly sits
somewhere in that range. The percentage table below uses the average as
its anchor.
Worked example. Lift 225 lb for 5 reps. Epley gives
225 × (1 + 5/30) = 262.5 lb; Brzycki gives
225 × 36 / (37 − 5) = 253.1 lb; the average is about
258 lb. From there, 80% is roughly 206 lb for sets of eight, and 90% is
roughly 232 lb for heavy triples.
Percentage-of-1RM training chart
A standard Epley-derived chart linking each percentage of your one-rep max to the rough
number of reps you can expect at that load. Enter your numbers in the calculator above and
the table fills in the actual weights; this reference version shows the relationship on its
own. Lighter loads are for technique and volume; heavier loads are for strength.
% of 1RM
Roughlyreps at this load
Typical usegeneral guidance
100%
1 rep
True max single
95%
2 reps
Strength
93%
3 reps
Strength
90%
4 reps
Strength
87%
5 reps
Strength
85%
6 reps
Strength / hypertrophy
83%
7 reps
Hypertrophy
80%
8 reps
Hypertrophy
77%
9 reps
Hypertrophy
75%
10 reps
Hypertrophy
70%
12 reps
Volume / endurance
67%
15 reps
Volume / endurance
Rep targets are approximate and vary by lift, training history, and how close to failure you
go. They describe a typical trained lifter; treat the chart as a starting point and adjust
based on how the loads actually feel.
Using the number well
An estimated 1RM is only useful if you apply it sensibly. Four things worth knowing before
you load the bar.
Lower reps mean a better estimate
The fewer reps between your set and a true single, the less the formula has to extrapolate, so a heavy triple or a set of five gives a far tighter estimate than a set of fifteen. Both formulas nearly match at low reps and diverge as reps climb. If you want a number you can trust, feed the tool your hardest low-rep set, not your longest one.
Pick a percentage for the goal
Strength work generally sits around 85–95% of your 1RM for low reps; hypertrophy, or muscle-building work, tends to live around 67–80% for higher reps; lighter loads below about 67% are useful for technique, speed, and warm-ups. The percentage table turns your estimated max into a concrete weight for each of those zones so you can program a session in a minute.
Treat the average as a planning number
Sleep, stress, nutrition, caffeine, and how grooved the lift is can swing your real max by several percent on any given day. Use the average estimate to set training loads, then adjust by feel: if the prescribed weight moves faster than expected, your max has likely gone up; if it grinds, back off rather than forcing it.
Don't chase the single unless you're ready
You almost never need to test a true 1RM — an estimate from a hard set of three to five reps gives nearly the same programming information without the risk. If you do test, build up with a thorough warm-up, keep your technique clean, and use a spotter or set safety pins or bars, especially on the squat and bench press. When in doubt, estimate.
Where to buy
Got your numbers? Here's where to pick up what you need:
The terms behind the calculator, in plain English. These are background definitions for the
math on this page, not coaching cues — follow a qualified coach and your own judgment
for how to actually train.
One-rep max (1RM)
The most weight you can lift for a single full repetition of an exercise with good form. It's the anchor for percentage-based programming, but testing it directly is risky, so it's usually estimated from a submaximal set rather than measured.
Epley formula
A 1RM estimate of weight × (1 + reps/30). It adds a fixed fraction of the lifted weight for each rep, producing a straight line that keeps rising with reps. Simple and widely used; see also Brzycki.
Brzycki formula
A 1RM estimate of weight × 36 / (37 − reps). Its denominator shrinks as reps rise, so the estimate accelerates and then breaks down near 37 reps, where it's undefined. Tends to read slightly lower than Epley at moderate reps.
Percentage of 1RM
A training load expressed as a share of your one-rep max — for example, 80% of a 258 lb max is about 206 lb. Programs prescribe percentages so the same plan scales to any lifter; the percentage chart maps each one to a rough rep target.
AMRAP set
"As many reps as possible" — a set taken to or near failure at a fixed weight. AMRAP sets are the ideal input for a 1RM estimate, because the reps-to-failure at a known load is exactly what the formulas convert into a projected single.
Hypertrophy
Training aimed at building muscle size, typically using moderate loads of roughly 67–80% of 1RM for higher reps. Distinct from pure strength work, which uses heavier loads and fewer reps; the percentage chart marks where each zone falls.
RPE (rate of perceived exertion)
A subjective 1–10 scale for how hard a set felt, where 10 means no reps left in the tank. RPE is an alternative to fixed percentages and a useful sanity check: if a load that should be 80% of your max feels like a 10, your estimated 1RM is probably too high that day.
Frequently asked
You estimate it from a set you actually lifted rather than testing a true single. Take the weight and the number of reps and run them through a 1RM formula. The two most common are Epley, which is weight × (1 + reps/30), and Brzycki, which is weight × 36 / (37 − reps). For example, 225 lb for 5 reps gives about 262.5 lb by Epley and 253.1 lb by Brzycki, for an average of roughly 258 lb. The calculator shows both formulas and their average so you see the range, not just one number.
They're two different equations fitted to lifting data; they agree closely at low reps and drift apart as reps climb. Epley adds a fixed fraction of the weight per rep (reps/30), so it keeps rising in a straight line. Brzycki divides by (37 − reps), so its estimate accelerates and then breaks down as reps approach 37, where it's undefined. At one rep both simply return the weight you lifted. For a set of five they differ by only a few percent; for a set of fifteen the gap is much larger — which is exactly why this tool averages them and warns you above about twelve reps.
Use a set of about one to ten reps, and ideally five or fewer. The fewer reps between your set and a true single, the smaller the gap the formula has to extrapolate, so the estimate is more accurate. A heavy triple or a set of five is an excellent input. Sets above twelve to fifteen reps involve so much fatigue and pacing that the estimate becomes unreliable, and the Brzycki formula is undefined at 37 reps because its denominator hits zero.
It depends on the goal. Strength work generally lives at about 85–95% of your 1RM for low reps (around two to six). Hypertrophy, or muscle-building work, tends to sit around 67–80% for higher reps (roughly eight to fifteen). Lighter work below about 67% is useful for technique, speed, and warm-ups. The percentage table lists the estimated load at each percentage of your 1RM alongside the rough reps it corresponds to, so you can pick a target and read the weight directly.
A true 1RM test carries real injury risk and shouldn't be done casually. Maximal singles demand a thorough warm-up, well-grooved technique, and a competent spotter or properly set safety pins or bars, especially on the squat and bench press. For most people, an estimate from a hard set of three to five reps gives almost the same training information without the risk — estimating with a calculator like this one is the safer default. Reserve actual max attempts for experienced lifters with proper coaching and safety equipment. This is general information, not training or medical advice.
Because Epley and Brzycki are different curves fitted to different data, and any formula is only an approximation of how strength and reps trade off for a real person. That trade-off also varies by lift, training history, and muscle fiber makeup, so no single equation is right for everyone. At low reps the formulas nearly match; the divergence grows with reps. Showing both plus their average is more honest than reporting one precise-looking figure, because the true value almost certainly sits somewhere in that range.
It's a good estimate, not a measurement. Accuracy is highest when the input set is five reps or fewer and taken close to failure, where the formulas only have to extrapolate a short distance. It degrades as reps rise, becoming unreliable above roughly twelve to fifteen reps. Day-to-day factors such as sleep, stress, caffeine, and how grooved the lift is can swing your real max by several percent, so treat the result as a planning number and adjust based on how the prescribed loads actually feel in the gym.
Common mistakes
Estimation formulas like Epley and Brzycki are built on specific assumptions about
rep speed, rest, and form. Inputs that violate those assumptions produce estimates
that are too high — sometimes dangerously so.
Attempting an actual 1RM without a spotter or rack
The whole point of the estimation approach is to avoid needing a true one-rep max test. A failed 1RM with no spotter or safety equipment is an injury risk, particularly on barbell bench press or squat. Use a submaximal set — 3 to 10 reps to near-failure with controlled form — and let the formula extrapolate. The estimate will be close enough for training purposes.
Using too many reps per set as the input
The Epley and Brzycki formulas are most accurate in the 1–6 rep range and lose reliability above 10 reps. A 15-rep set introduces more variability: fatigue accumulates, pace changes, and the relationship between reps-at-weight and true 1RM becomes less predictable. For the best estimate, use a weight that takes you to near-failure in 3–6 clean reps.
Counting reps where form broke down
If the last two reps of your set involved a significant form change — a hitch, a grind, half the range of motion — those reps don't belong in the count. The formulas assume consistent, full-range repetitions. Including technique-compromised reps inflates the estimate and produces a 1RM target that may exceed what your mechanics can safely support.
Expecting the estimate to match across all exercises
1RM estimation accuracy varies by movement. It works well for compound barbell lifts (squat, bench, deadlift). It is less reliable for isolation exercises, machine-based movements, or exercises where fatigue accumulates differently. Treat the estimate as a training-plan starting point, not a certified max, especially on movements you haven't tested recently.