Squat 1RM from 15 Reps — Epley and Brzycki Estimate
If you can squat 120 kg for 15 reps, your estimated one-rep max is 188.2 kg — the average of the Epley estimate (180.0 kg) and the Brzycki estimate (196.4 kg). That is the headline number, and the rest of this page shows exactly how it was calculated, what loads to train with at every percentage of it, and how far you should trust it.
The Squat works the quadriceps, glutes and hamstrings, and it is a barbell lift. An intermediate lifter often squats around 1.5 times bodyweight, so a 120 kg squat for an 80 kg lifter is a solid intermediate number. The worked example below uses a 15-rep set with 120 kg as the load — that is an assumption for illustration, not a prescription for you. Put your own weight and reps into the One Rep Max Calculator and the same two formulas will estimate your own max in seconds.
An estimated one-rep max matters because almost every serious strength programme is written in percentages of it. "Five sets of five at 80%" only means something if you know what 100% is, and testing a true one-rep max is risky, fatiguing and unnecessary for most lifters. A submaximal set of 15 reps gives you the number without the risk — provided you understand the limits of the formulas, which this page sets out honestly.
Use the one-rep-max calculator for your own numbers
The worked example on this page uses 120 kg for 15 reps. Your numbers will be different, and the calculator does the same maths with them. Use the Squat 1RM Calculator for this lift, or the general One Rep Max Calculator for any lift, and you will get the Epley estimate, the Brzycki estimate, their average, and the full training-percentage table for your own max.
For comparison, here are the other one-rep-max pages for the squat — the same two formulas applied to different rep counts:
- Squat 1RM from 12 Reps — Epley and Brzycki Estimate
- Squat 1RM from 10 Reps — Epley and Brzycki Estimate
- Squat 1RM from 3 Reps — Epley and Brzycki Estimate
The formulas, shown and cited
Two published formulas estimate a one-rep max from a submaximal set. Both are shown here with their sources, and both are worked through with this page's numbers.
Epley (Epley 1985): 1RM = weight × (1 + reps ÷ 30)
Brzycki (Brzycki 1993): 1RM = weight × 36 ÷ (37 − reps)
Worked through for 120 kg × 15 reps on the squat:
- Epley: 120 × (1 + 15 ÷ 30) = 120 × 1.5 = 180.0 kg
- Brzycki: 120 × 36 ÷ (37 − 15) = 120 × 36 ÷ 22 = 196.4 kg
- Average of the two: (180.0 + 196.4) ÷ 2 = 188.2 kg (415 lb)
The two formulas differ by 16.4 kg on this set. At 15 reps the formulas are outside their comfort zone, and you can see it in the gap: they differ by 8.7 percent here. A 15-rep set is an endurance test as much as a strength test — breathing, conditioning and mental toughness matter as much as maximal strength, and the formulas cannot separate those. Treat the average as a rough guide only, not a number to plan a strength block around. If you want a tighter estimate, re-test with a set of 5 to 8 reps; the 15-rep figure is most useful for setting endurance loads and for tracking whether your high-rep strength is improving over time.
Neither formula is magic. Both were fitted to real lifting data, and both assume the set was taken close to failure with good technique — a set of 15 reps with two more reps left in the tank will underestimate your max, because the formulas assume those 15 reps were hard. If you stopped well short of failure, add that to your interpretation: the estimate is a floor, not a ceiling. And if your technique broke down on the last rep, the set does not count for estimation purposes at all.
Training percentages for a 188.2 kg squat max
Most programmes prescribe loads as a percentage of your one-rep max. The table below gives the load for every percentage from 50% to 100% of the 188.2 kg estimate, so you can read your working weights straight off it without doing the multiplication in your head between sets.
| % of 1RM | Load (kg) | Load (lb) |
|---|---|---|
| 50% | 94.1 kg | 207 lb |
| 55% | 103.5 kg | 228 lb |
| 60% | 112.9 kg | 249 lb |
| 65% | 122.3 kg | 270 lb |
| 70% | 131.7 kg | 290 lb |
| 75% | 141.1 kg | 311 lb |
| 80% | 150.5 kg | 332 lb |
| 85% | 160.0 kg | 353 lb |
| 90% | 169.4 kg | 373 lb |
| 95% | 178.8 kg | 394 lb |
| 100% | 188.2 kg | 415 lb |
How those percentages are used in practice depends on the goal. Strength work lives at 85–95% of 1RM for sets of 1–5 reps, with long rests of three to five minutes. Hypertrophy work lives at 65–85% for sets of 6–12 reps, with rests of 60–120 seconds. Muscular endurance work lives at 50–65% for sets of 15 or more reps, with short rests. The same max produces all three training zones; what changes is the percentage and the rep count, not the lift.
A practical example: if your programme calls for five sets of five at 80% on the squat, that is 150.5 kg for five reps, five times, with three minutes of rest between sets. If it calls for three sets of ten at 70%, that is 131.7 kg for ten reps, three times, with 90 seconds of rest. The table above is the only arithmetic you need; the programme supplies the sets, reps and rest.
What you can lift for other rep counts
If your estimated max is 188.2 kg, the table below gives the load you should be able to handle for each rep count, worked out from the Epley relationship between reps and percentage of maximum. Use it to pick weights for any set in your programme, not just the ones at your tested rep count.
| Reps | Estimated load (kg) | Estimated load (lb) |
|---|---|---|
| 1 | 182.1 kg | 401 lb |
| 2 | 176.4 kg | 389 lb |
| 3 | 171.1 kg | 377 lb |
| 5 | 161.3 kg | 356 lb |
| 6 | 156.8 kg | 346 lb |
| 8 | 148.6 kg | 328 lb |
| 10 | 141.1 kg | 311 lb |
| 12 | 134.4 kg | 296 lb |
| 15 | 125.5 kg | 277 lb |
| 20 | 112.9 kg | 249 lb |
The row for 15 reps reads 125.5 kg, which sits within a kilogram or two of the 120 kg used in the worked example — the small difference is because this table is built from the averaged estimate rather than from either formula alone. That is the honest way to read it: the table is a guide for choosing weights, and the right weight on the day is the one you can lift with good technique for the prescribed reps, not the number in the cell.
How to use the result, and how to progress safely
Use the 188.2 kg figure as a planning number, not as a weight to attempt tomorrow. The safest way to use an estimated max is to base your training percentages on it for four to six weeks, then re-test with a fresh submaximal set and update the estimate. If the new set gives a higher estimate, your training weights go up; if it gives the same number, you have maintained; if it gives a lower number, you may be under-recovered and need a lighter week.
Add 2.5 kg to the bar when you complete all prescribed sets and reps at a given weight for two sessions in a row. Train the squat twice a week with at least 48 hours between hard sessions, and keep one of those sessions lighter — the squat is the most systemically fatiguing lift most people do.
Warm up properly before any heavy set. For a squat session, that means the empty bar, then 50 percent of your working weight for a few reps, then 70 percent, then your working sets — never jumping straight from the warm-up to a heavy load, and always rehearsing depth with the light sets. And never test a true one-rep max alone, without spotters or safety bars. The whole point of estimating from a 15-rep set is that you never have to find out what your true max is by attempting it.
Recovery is part of the programme, not a break from it. The squat stresses the quadriceps, glutes and hamstrings, and those muscles need 48–72 hours before they are trained hard again. Sleep, food and rest days are where the strength is actually built; the training session is just the stimulus. A lifter who adds weight to the bar every week while sleeping five hours a night will stall and then regress, and no formula can fix that.
Technique standards for the squat
The squat is performed with the bar across the upper back, feet about shoulder-width apart, braced hard through the trunk, sitting back and down until the hip crease passes below the top of the knee, then driving back up. Depth is the standard that matters most for estimation: a shallow squat lets you handle far more weight, so a rep count from quarter squats will produce an inflated max. A set only counts if every rep reaches depth with the heels on the floor and the knees tracking over the toes. Film your sets from the side if you are unsure — most lifters squat higher than they think.
The most common errors are cutting depth, letting the knees cave inward, lifting the heels, and letting the chest collapse so the squat turns into a good morning. Each of these lets you handle more weight or more reps with worse technique, and each of them inflates the estimate.
What the number does NOT tell you
An estimated one-rep max is a useful number with clear limits. First, it is an estimate, not a measurement. Your true max can only be found by attempting a maximum lift, and the estimate can be off by 5–10% in either direction even from a good set. That is why the percentage table above should be treated as a guide: if 80% feels like 90% on the day, trust the feeling, not the table.
Second, the formulas assume good technique. A squat performed with a shortened range of motion or momentum will produce a higher rep count than a strict set, and the formulas will reward that with an inflated max. Compare estimates only between sets done the same way — same depth, same pause, same standard. A stricter set that gives a lower estimate is more useful than a sloppy set that gives a higher one.
Third, a one-rep max says nothing about your health, your body composition or your overall fitness. It measures one thing — the most weight you can lift once in this movement — and a big number in one lift does not imply a big number in another, let alone general health. It also says nothing about injury risk: a lifter with a large estimated max and poor technique is closer to an injury than a lifter with a modest max and excellent technique.
Finally, the formulas are population tools. They were fitted to groups of lifters, and individuals vary. Some lifters are naturally better at high reps than at singles, and the formulas will underestimate their max; others are the opposite, and the formulas will overestimate. Over time you will learn your own pattern — whether your true max tends to sit above or below the estimate — and you can adjust your training percentages accordingly.
Frequently asked questions
What is my squat 1RM if I lift 120 kg for 15 reps?
Using the worked example on this page: Epley gives 180.0 kg and Brzycki gives 196.4 kg, so the averaged estimate is 188.2 kg. That figure assumes the 15-rep set was taken close to failure with good technique. For your own weight and rep count, use the Squat 1RM Calculator.
Which formula is better, Epley or Brzycki?
Neither is clearly better in general — that is why this page averages them. Epley (1985) tends to give slightly higher estimates at higher rep counts, while Brzycki (1993) is often a little more conservative. From sets of ten reps or fewer the two usually agree within a few kilograms, and the average is a sensible compromise. Above ten reps both become less reliable, and the gap between them — 16.4 kg here — is a warning sign rather than a detail to average away.
Why is a 1RM estimated from 15 reps less reliable?
Because both formulas were fitted to low-rep data, and at 15 reps the set tests endurance and conditioning as much as maximal strength. Epley and Brzycki diverge sharply at high reps, so their average is a rough guide rather than a precise number. Use it to set endurance loads and to track high-rep progress, and re-test at 10 reps or fewer when you need a number to plan heavy training around.
How deep should my squat be for the estimate to count?
The hip crease should pass below the top of the knee on every rep. Shallower squats let you handle far more weight, so a rep count from quarter squats will produce an inflated max. Film your sets from the side if you are unsure — most lifters squat higher than they think, and depth is the first thing to check when an estimate looks too good.
What weight should I train with for strength on the squat?
Strength work is usually 85–95% of your estimated max. For a 188.2 kg max, that is 160.0 kg to 178.8 kg, for sets of 1–5 reps with three to five minutes of rest. For muscle growth, use 65–85% (122.3–160.0 kg) for sets of 6–12 reps. The full percentage table above covers every step from 50% to 100%.
How often should I re-test my squat max?
Every four to eight weeks is enough for most lifters. Testing more often wastes training time and adds fatigue without new information, because strength changes slowly. Re-test with the same rep count and the same technique standard as last time, so the two estimates are genuinely comparable, and update your training percentages from the new figure.
Related pages
Estimates only, not medical advice. Minimum safe intakes: 1,200 kcal/day women, 1,500 kcal/day men — consult a healthcare professional before a very-low-calorie diet.