Tools
Squat max calculator
Enter a hard squat set, the weight and the reps, and the calculator estimates your squat max with the Epley formula, with five other published formulas beside it. Read the number as a guide: one study of seven formulas, as reported in a later paper, found that only one matched tested squat maxes. A set of five reps or fewer gives the closest estimate.
Estimated one-rep max Epley
140kg
An estimate, not a tested max.
120 kg for 5 reps gives an estimated one-rep max of 140 kg.
Past 12 reps the formulas drift far apart. Read this as a rough guide; a heavier set of fewer reps gives a closer number.
20 kg bar + 60 kg per side
The bar is drawn at 140 kg, the nearest weight you can load.
Six formulas, one set
The same set through six published formulas. Each mark sits on one scale, from the lowest answer to the highest.
The six formulas put this set between 135 and 142.8 kg: a spread of 7.8 kg, or 5.6% of the headline.
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Epley Headline 140 kg
weight × (1 + reps ÷ 30)
-
Brzycki 135 kg −5 Against Epley
weight × 36 ÷ (37 − reps)
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Lander 136.5 kg −3.5 Against Epley
100 × weight ÷ (101.3 − 2.67123 × reps)
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O'Connor 135 kg −5 Against Epley
weight × (1 + 0.025 × reps)
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Lombardi 141 kg +1 Against Epley
weight × reps^0.10
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Mayhew 142.8 kg +2.8 Against Epley
100 × weight ÷ (52.2 + 41.9 × e^(−0.055 × reps))
Lowest 135 kgHighest 142.8 kg
Percentage chart
Loads from 50 to 100% of the estimate, each rounded to the nearest weight the bar and plates can make.
| Percent | Load | Each side | Exact |
|---|---|---|---|
| 100% | 140 kg | 25 + 25 + 10 | 140 |
| 95% | 132.5 kg | 25 + 25 + 5 + 1.25 | 133 |
| 90% | 125 kg | 25 + 25 + 2.5 | 126 |
| 85% | 120 kg | 25 + 25 | 119 |
| 80% | 112.5 kg | 25 + 20 + 1.25 | 112 |
| 75% | 105 kg | 25 + 15 + 2.5 | 105 |
| 70% | 97.5 kg | 25 + 10 + 2.5 + 1.25 | 98 |
| 65% | 90 kg | 25 + 10 | 91 |
| 60% | 85 kg | 25 + 5 + 2.5 | 84 |
| 55% | 77.5 kg | 25 + 2.5 + 1.25 | 77 |
| 50% | 70 kg | 25 | 70 |
Rep maxes
The weight the Epley formula expects for 1 to 12 reps at this max. The marked plate is the rep count you typed.
| Reps | Load | Of max | Exact |
|---|---|---|---|
| 1 | 140 kg | 100% | 140 |
| 2 | 130 kg | 94% | 131.3 |
| 3 | 127.5 kg | 91% | 127.3 |
| 4 | 122.5 kg | 88% | 123.5 |
| 5 | 120 kg | 86% | 120 |
| 6 | 117.5 kg | 83% | 116.7 |
| 7 | 112.5 kg | 81% | 113.5 |
| 8 | 110 kg | 79% | 110.5 |
| 9 | 107.5 kg | 77% | 107.7 |
| 10 | 105 kg | 75% | 105 |
| 11 | 102.5 kg | 73% | 102.4 |
| 12 | 100 kg | 71% | 100 |
Squat: what the studies found
A study of seven formulas, as reported in source 2, found that only one matched tested squat maxes. It is a formula by Wathan, which this page does not print because we could not read a source for its exact form.
The closest lower-body data in the study we read in full is the leg press, not the squat. There the authors found that Brzycki, Lander and O'Connor underestimated strength, and that Epley had some of the smallest average errors, leaning slightly high. Every formula did worse from ten-rep sets than from five-rep sets.
The estimate describes the squat you did: a max at the same depth and in the same style as the reps you entered.
How the estimate is worked out
The headline uses the Epley formula: estimated max = weight × (1 + reps ÷ 30). It is the formula the Masheen app uses for every set you log, so the estimate here and the estimate in the app come from the same sum.
The other five formulas run on the same weight and reps. At one rep this page returns the weight you lifted for every formula: you have shown you can lift it, and there is nothing to estimate.
Some tables print the Epley factor as 0.033 per rep, and the Brzycki formula as weight ÷ (1.0278 − 0.0278 × reps). Both are the same lines written another way.
| Formula | Published form | Credited to |
|---|---|---|
| Epley | weight × (1 + reps ÷ 30) | Boyd Epley, 1985 |
| Brzycki | weight × 36 ÷ (37 − reps) | Matt Brzycki, 1993 |
| Lander | 100 × weight ÷ (101.3 − 2.67123 × reps) | Lander, 1985 |
| O'Connor | weight × (1 + 0.025 × reps) | O'Connor, Simmons and O'Shea, 1989 |
| Lombardi | weight × reps^0.10 | Lombardi, 1989 |
| Mayhew | 100 × weight ÷ (52.2 + 41.9 × e^(−0.055 × reps)) | Mayhew, Ball, Arnold and Bowen, 1992 |
When the estimate stops being trustworthy
A formula turns one set into a guess about a different effort. The further the set is from a single, the weaker the guess.
In a study of 70 adults aged 18 to 69, the closest predictions came from a five-rep set, and accuracy fell as the reps to failure went up. The authors conclude that no more than ten reps belong in the straight-line formulas, and every formula they compared did worse on ten-rep sets than on five-rep sets.
The spread on this page shows the same thing. At five reps the six formulas sit within about 6 percent of each other. At fifteen they are more than 20 percent apart. Past 12 reps the page marks the result as rough, as the app's own calculator does.
The set has to be a hard one. Every formula assumes the reps were close to the most you could do with that weight; an easy set gives a low number.
Bench press, squat and deadlift
The formulas are the same for every lift. How well they fit is not.
- Bench press max calculator. One study, as reported in a later paper, found two of seven formulas matched tested bench press maxes.
- Squat. One study, as reported in a later paper, found one of seven formulas matched tested squat maxes.
- Deadlift max calculator. One study, as reported in a later paper, found seven formulas all came out 9 to 14 percent under the tested deadlift max.
- One-rep max calculator.
Other lifts. The formulas take any weight and reps: incline or close-grip bench, rows, dumbbells, kettlebells. None of the six was built on those lifts in the sources we read, so read the number as a rough guide. For dumbbells, the result is a dumbbell number; nothing here converts it to a barbell lift.
How the chart rounds
Each row takes a percentage of the estimated max and moves it to the nearest weight you can build: the bar plus pairs of plates. With plates down to 1.25 kg that is a step of 2.5 kg; with plates down to 2.5 lb it is a step of 5 lb. When a figure falls exactly between two loads the chart takes the lower one, as the app does.
The "Exact" column shows the figure before rounding, so you can see how far each load moved.
The rep-max table turns the Epley formula round: max ÷ (1 + reps ÷ 30). It carries the same doubt as the estimate it starts from.
Sources
Read on 12 November 2026.
- Reynolds JM, Gordon TJ, Robergs RA. Prediction of one repetition maximum strength from multiple repetition maximum testing and anthropometry. Journal of Strength and Conditioning Research, 2006; 20(3): 584–592. The published forms of the Brzycki, Epley, Lander, O'Connor, Lombardi and Mayhew formulas (its Table 5); the five-rep and ten-rep findings; the finding on body measurements.
- Eston R, Evans HJL. The validity of submaximal ratings of perceived exertion to predict one repetition maximum. Journal of Sports Science and Medicine, 2009; 8: 567–573. Reports the results of LeSuer and others (1997) on seven formulas in the bench press, squat and deadlift. We could not open the 1997 paper itself.
- One-repetition maximum. Wikipedia. The Epley formula written as weight × (1 + reps ÷ 30) and the Brzycki formula as weight × 36 ÷ (37 − reps).
Questions
Are one-rep max calculators accurate?
They give an estimate. In a study of 70 adults, predictions from a five-rep set were the closest and they got worse as the reps went up. Lifts differ too: a later paper reports an earlier study in which seven formulas all came out 9 to 14 percent under the tested deadlift max.
Which one-rep max formula is the most accurate?
No formula wins on every lift. In one study Epley had some of the smallest average errors, while Brzycki and O'Connor were among the closest on the chest press. That is why this page prints six and shows the gap between them.
What is the Epley formula?
Estimated max = weight × (1 + reps ÷ 30). Lift 100 kg for 5 reps and it gives 116.7 kg. It is credited to Boyd Epley, 1985, and it is the formula the Masheen app uses.
How many reps give the closest estimate?
Five or fewer, taken close to the most you could do. The study behind that says to use no more than ten reps with the straight-line formulas. Past 12 reps this page still answers and marks the number as rough.
What is the difference between Epley and Brzycki?
Epley is weight × (1 + reps ÷ 30). Brzycki is weight × 36 ÷ (37 − reps). They give the same answer at 10 reps. Below 10 Epley is a little higher; above 10 Brzycki climbs faster.
Do body weight, age or sex change the estimate?
Not in these formulas: they use only the weight and the reps. In the study this page leans on, adding body measurements, sex and training volume to the equation did not make the prediction better.