Updated September 2026 Calculate your 1RM for any lift and get a full percentage-based training chart — no need to max out.
For best accuracy, use a set of 3–8 reps at a challenging weight. Estimates become less accurate beyond 10 reps.
How to use your 1RM
Your estimated 1RM is the foundation of percentage-based training (PBT), used in powerlifting programs like 5/3/1, Sheiko, and GZCLP. Rather than maxing out (which is fatiguing and risky), you test a heavy set of 3–8 reps and estimate your max from there.
The percentage chart below your result shows how much to load for different rep ranges and training intensities. For example, working at 80% of your 1RM for sets of 5 is a common strength-building zone.
The three formulas, and when they agree
Every rep-max formula predicts a one rep max from a weight lifted for a known number of repetitions taken to or near failure. W is the weight, R the reps.
Brzycki: 1RM = W × 36 ÷ (37 − R)
Lombardi: 1RM = W × R0.10
They agree closely at low reps and diverge sharply as reps rise. Take a set of 100 kg and watch the spread widen:
| Reps at 100 kg | Epley | Brzycki | Lombardi | Spread |
|---|---|---|---|---|
| 2 | 107 | 103 | 107 | 4 kg |
| 3 | 110 | 106 | 112 | 6 kg |
| 5 | 117 | 113 | 117 | 4 kg |
| 8 | 127 | 124 | 123 | 4 kg |
| 10 | 133 | 133 | 126 | 7 kg |
| 15 | 150 | 150 | 131 | 19 kg |
That pattern is the single most useful fact about rep-max estimation. At five reps the formulas sit within four kilograms of each other, so the choice barely matters. At fifteen they disagree by nineteen, and the output is no longer describing maximal strength at all.
Why accuracy collapses above five reps
- You stop measuring strength. A set of fifteen ends because of metabolite accumulation and fatigue resistance, not because you reached the limit of force production. That is muscular endurance wearing a strength label.
- Endurance varies enormously between people. Two lifters with the same 140 kg max might manage 8 and 14 reps at 100 kg, depending on fibre type, training history and pain tolerance. One equation cannot describe both.
- Lifts behave differently. Leg press and squat generally allow more reps at a given percentage than bench press does, and isolation movements behave differently again.
The practical rule: estimate from 2 to 5 reps for good accuracy, 6 to 8 for acceptable accuracy, and treat anything above 10 as a rough guide only. Never compare an estimate taken from a set of 12 with one taken from a set of 3.
Getting a good input set
The formula is rarely the limiting factor — the quality of the set you feed it is.
- Take the set within one or two repetitions of failure. A set of eight that could have been twelve produces a badly low estimate.
- Count only reps you would count in competition. Repetitions that degrade in range of motion are a different exercise.
- Use a compound lift. Squat, bench, deadlift and overhead press behave predictably; isolation work does not.
- Be fresh. A set taken at the end of a long session underestimates, sometimes badly.
- Keep conditions constant across months — same lift, similar rep range, similar point in the session.
Programming from an estimate
Most strength programmes prescribe percentages of a one rep max, which is exactly what this estimate is for.
| % of 1RM | Typical reps | What it trains |
|---|---|---|
| 95–100% | 1–2 | Maximal strength, largely neural |
| 90–95% | 2–4 | Strength |
| 85–90% | 4–6 | Strength with some hypertrophy |
| 75–85% | 6–10 | Hypertrophy |
| 65–75% | 10–15 | Hypertrophy and endurance |
| Under 65% | 15+ | Endurance and technique work |
Two adjustments make this work in practice. Programme from the most conservative of the three estimates, so the training feels manageable rather than crushing. And update every four to six weeks rather than every session — daily performance varies with sleep, food and stress far more than real strength does. The full treatment is in how to estimate your one rep max without testing it.
When to use RPE instead
Percentage-based programming assumes your max today equals your max when you calculated it, which it never quite does. On a bad day, 85 percent feels like 92. Rating of perceived exertion — usually expressed as repetitions in reserve — prescribes effort instead of load, so the weight adjusts to the day you are having. In practice, use an estimated max to plan the block and RPE to adjust on the day.
1RM calculator — FAQ
No single formula is best for everyone — accuracy varies by individual. The Epley formula tends to perform well across a wide range of lifters. Brzycki is often more accurate for lower rep ranges (1–6 reps). Using the average across multiple formulas gives a more robust estimate. The key variable is rep count: estimates from 3–6 reps are far more accurate than estimates from 10+ reps.
Not without proper preparation. A true 1RM attempt requires a thorough warm-up, a spotter for upper body lifts, and ideally experience with heavy singles. For most gym-goers, working at 85–95% of estimated 1RM for 2–3 reps is safer and nearly as effective for strength development. Save true max attempts for competition or carefully planned peaking cycles.
In the 2 to 5 rep range they agree within a few kilograms, so it barely matters. Brzycki is the most conservative and a sensible default for programming. The rep range you estimate from matters far more than the formula you choose.
For programming purposes, close enough — and considerably cheaper. Testing a true max requires a full warm-up progression, spotters and complete recovery, and leaves enough fatigue to compromise the following days of training.
Usually because the input set was not close enough to failure, or came from too high a rep count. A true single also demands technical competence and psychological readiness that a set of eight does not develop.
Every four to six weeks. Updating more often mostly tracks day-to-day variation in sleep, stress and food rather than genuine changes in strength.