Enter a set's weight and reps to calculate an estimated one-rep max, plus percentage-based loads. The estimate is most useful when the set was challenging and performed with the technique you want to compare.
A formula is not a tested maximum. Use the result as a starting reference and follow the trend across comparable sets, rather than assuming the predicted single is a weight you should attempt today.
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One rep max calculator
Estimate your 1RM from a recent hard set with the Epley equation, then see practical training loads.
Estimated one rep max
265 lb
- 70%
- 185 lb
- 80%
- 210 lb
- 90%
- 235 lb
Estimates are most useful from technically consistent, high-effort sets of about 2–6 reps. Use a spotter and sound judgment before attempting any heavy single.
How to calculate your one rep max
The most widely used estimate is the Epley equation:
estimated 1RM = weight × (1 + reps ÷ 30)
So 225 for five reps gives 225 × (1 + 5 ÷ 30) = 262.5, or roughly a 260 lb max. Run the arithmetic in your head if you like; the calculator above just does it faster and rounds the training loads to the nearest plate increment.
Two rules make the answer trustworthy. First, use a genuinely hard set. An estimate from a set you stopped four reps early is an estimate of a set you did not do. Second, keep the rep count low. Every formula drifts as reps climb, because endurance starts contributing more than maximal force, so a set of three predicts far better than a set of twelve.
What percentage of your max should you lift?
Because the formula is reversible, it also produces the percentage chart people usually want next: what a given rep count implies about your max, and what load a given percentage should feel like.
| Reps at that weight | Roughly this % of your 1RM | Commonly used for |
|---|---|---|
| 1 | 100% | Testing, competition, occasional heavy singles |
| 2 | 94% | Heavy skill work near the top end |
| 3 | 91% | The standard heavy top set in strength programs |
| 5 | 86% | The most common working-set intensity for strength |
| 8 | 79% | Hypertrophy-range work |
| 10 | 75% | Higher-rep accessory and volume work |
| 12 | 71% | Volume, conditioning, and technique-light movements |
These are Epley-derived approximations, not measurements. Real lifters vary. Some people are built for singles and fall apart at ten, others the reverse, and the same person varies by lift, because a deadlift and a strict press do not fatigue the same way. Treat the row as a starting point and let your own logged sets correct it.
Estimated 1RM beats tested 1RM for tracking
A true max test is fatiguing, technique-sensitive, and hard to repeat weekly. An estimated 1RM, usually written e1RM, computed from your best recent rep work gives you the same signal on an ordinary training day, with no psych-up and no spotter required.
Every formula is an approximation. Accuracy drops as reps climb past five or six, and it varies by lift and by lifter. That is fine, because the point is not the exact number; it is whether the number is moving. A steady e1RM at falling RPE is progress too, since the same load for the same reps at a lower effort is a stronger lifter even though the estimate did not budge.
How far to trust the estimate on your lift
One equation is being asked to describe every barbell movement for every lifter, and it manages that by describing the average of them. Two things push your real max away from the number on this page.
The first is the exercise. How many reps you can complete at a fixed percentage of your max is not constant across lifts, and researchers who publish loading tables have to publish separate ones for the bench press and the leg press because the curves genuinely differ. How much muscle the movement recruits is part of it: large lower-body exercises have been shown to allow more reps at the same relative load than a bench press or a curl. A high-rep deadlift set adds a wrinkle of its own, since grip and breathing often end it before the hips and back are finished, which is why deadlift estimates are usually taken from sets of five or fewer.
The second is you. In the studies that measured reps to failure at set percentages, the variation between individuals was wide enough that the authors advised practitioners against prescribing from standard repetition charts at all. Some lifters beat the table at low reps and fall short of it at high ones, and some do the reverse, and there is no way to tell from the outside which one you are.
Both problems shrink as the reps come down, because a set of three leaves less room for endurance, grip, and breathing to change the answer. Estimate from two to five reps and the exact lift barely matters. Estimate from a set of ten and it matters a great deal.
Calibrate the formula against your own sets
You are not stuck with the average, because you have your own history and the comparison is one question.
Ask for your estimated max on a lift charted next to your heaviest actual set on the same lift, over the same window. When the two lines track each other, the formula fits you on that movement. When the estimate rides consistently above the real top set, the equation is flattering you at that rep range, and the fix is to program off your logged top sets rather than off the percentage table.
Do it per lift rather than once. It is normal for the estimate to fit your bench press and overshoot your deadlift, and finding that out costs nothing beyond sets you were already doing.
Two conditions keep the comparison clean. Compare sets at similar rep counts, since a five-rep estimate and a ten-rep estimate are not the same instrument. And compare sets taken at a similar time of day, because strength runs measurably higher in the late afternoon than it does early in the morning; the best time to work out guide covers how large that difference is and why it stops mattering over a training block.
"Chart my estimated max and my heaviest actual set for squat and for deadlift over the last four months, and tell me which lift the estimate fits better."
Turn a one-off number into a tracked metric
Here is where a calculator page usually stops and a logbook keeps going. The number above is a projection from one set on one day. What you actually want to know is the direction it has moved since spring.
ChatRPE closes that gap in two ways, and they are worth separating. The first is the measurement you already own: ask it to chart your heaviest actual set on a named lift and it pulls the maximum from that exercise across every session you have logged, giving you a line built from real work rather than arithmetic. "Chart my top set on bench press for the last six months" is the whole request.
The second is the estimate itself, charted the same way. The coach applies the Epley equation to every set in the window you ask about, keeps the best result from each session, and draws the line, so an e1RM trend going back six months comes out of sets you logged months before anyone mentioned the word e1RM.
Nothing has to be calculated in advance or saved as a separate number first; the estimate is derived from the weight and reps already in your logbook at the moment the chart is drawn. That is the practical difference between a calculator and a coach with your history: the calculator gives you 262.5 and forgets it, and the logbook shows you that number next to the one from March.
The same machinery handles anything else built from the numbers you log, which is worth knowing because e1RM is rarely the only question. Total volume per session is weight times reps summed; relative intensity is your working weight over your estimated max; a squat-to-bench ratio is one estimate divided by the other. All of them are charts you can ask for in a sentence, on their own axis if the scales differ, without adding anything to what you already track.
"Chart my estimated max on bench for the last six months and put my top set on the same chart, so I can see whether the estimate is tracking the real lift."
Log sessions in plain language with the workout log workflow, then let the progressive overload review decide when the trend justifies heavier prescriptions. If the top-set line has gone flat, that is a programming question rather than a maths one, and the how to get stronger guide covers the levers: specificity, heavy low-rep work, real rest between top sets, and the progression rule that replaces beginner linear progression once it runs out. If it has gone flat and the same weights are arriving at a higher RPE, look at fatigue first; the deload week guide covers reading that difference.
Frequently asked questions
How do I calculate my 1RM?
Take a hard set, then apply Epley: weight × (1 + reps ÷ 30). A set of 185 for eight gives 185 × (1 + 8 ÷ 30) ≈ 234 lb. The calculator on this page does it for any set of one to twelve reps and also shows the 70%, 80%, and 90% training loads. Use a set you genuinely pushed and keep the reps low, because both the effort and the rep count determine how far the estimate drifts.
How accurate are one rep max calculators?
Good enough for programming, not for bragging rights. Estimates from sets of two to five reps are typically close; estimates from high-rep sets drift further, and the drift is personal rather than random, since some lifters out-perform the formula at low reps and under-perform it at high ones. It also depends on the exercise, because rep capacity at a given percentage differs between lifts. The way to find out where you sit is to chart estimates against your own heaviest logged sets, lift by lift, which is a comparison a training log makes possible and a web form does not.
Does the 1RM formula work the same for squat, bench press, and deadlift?
Not exactly. The number of reps you can complete at a given percentage of your max varies by exercise, which is why published loading tables are exercise-specific rather than universal. One equation applied to all three lifts will fit some of them better than others for you personally. Keeping the estimate to sets of five or fewer narrows the gap, and charting the estimate against your real top set on each lift tells you which way yours leans.
Should a beginner test a true 1RM?
Usually not. Early on, technique changes faster than strength, so a max test measures skill under load more than strength itself. An estimated max from rep work is safer, repeatable, and just as useful for setting training weights. Use a spotter and sound judgment before attempting any heavy single, whatever your experience level.
What is e1RM?
Estimated one rep max: the maximum predicted from a submaximal set. Lifters track e1RM over time because it can be computed from normal training, which makes it a repeatable, low-risk progress metric. You get a strength reading every week instead of every training block.
How often should I test or re-estimate my max?
Re-estimate whenever you hit a notably good set, which for most people is every few weeks without planning for it. Actually testing a true single is worth doing rarely, before a competition or at the end of a block when you want a real number, because the test itself costs you a session's worth of recovery. The progressive overload guide covers reading the trend between those tests.
Can I estimate my max from a set of 10?
You can, and the calculator accepts it, but treat the result as a rough bracket rather than a number. At ten reps, how long you can sustain effort starts mattering as much as how much force you can produce, and the two do not track each other closely. If you want a usable estimate, take one set of three to five at a weight you would not want to add to.
What is the best one rep max calculator app?
For the arithmetic alone, any of them will do. It is one line of algebra, and the calculator on this page is free and needs no account. The difference worth paying attention to is whether the number connects to anything. ChatRPE keeps the sets themselves in one Universal Logbook, runs the estimate across all of them on request so the trend goes back as far as your training does, charts your heaviest actual set per lift alongside it, and flags a personal record as you log it, so the number sits on top of a history instead of being retyped from scratch every time you want it.