One Rep Max Calculator
Estimate your one-rep max and get a full %1RM training table.
Convert a measurement
One Rep Max Calculator — your inputs
- Weight lifted
- 100 kg
- Reps completed
- 5 reps
- Unit system
- Metric
Key takeaways
- An estimated 1RM from a set of 2–6 reps is accurate to within a few percent. From 12+ reps it is a guess.3
- Epley and Brzycki agree at 10 reps and diverge either side of it — Brzycki reads lower at high reps, Epley higher.
- Testing a true 1RM is rarely necessary. The estimate is accurate enough to program from, and carries none of the injury risk.
- Use the %1RM table to set working weights, then let performance update the estimate rather than re-testing.
- It is barbell-lift specific. A bench press estimate says nothing useful about your squat.
How to use this calculator
Enter the weight you lifted and the reps you completed.
Use a weight you can lift for 10 reps or fewer for best accuracy.
Understanding your result
Your one-rep max is the heaviest load you could lift once. Rep-max formulas estimate it from a lighter set taken close to failure.
The %1RM table below converts your 1RM into training weights for different rep ranges.
How a rep max becomes a 1RM
The relationship between load and how many reps you can do with it is remarkably consistent across trained lifters. Everyone can do roughly 10 reps with about 75% of their max, and roughly 5 with about 87%. The prediction equations simply invert that relationship: tell them the weight and the reps, and they tell you the load that would be a single.
Boyd Epley published his version in 1985 as a poundage chart for the Nebraska strength programme.1 Matt Brzycki published a different fit in 1993.2 Both are curve fits to observed data rather than derivations from physiology, which is why they agree in the middle of the range and drift apart at the edges.
| Reps | % of 1RM | Typical use |
|---|---|---|
| 1 | 100% | Testing, competition |
| 2 | 95% | Peaking, heavy singles work |
| 3 | 93% | Strength |
| 5 | 87% | Strength — the most popular working range |
| 6 | 85% | Strength / hypertrophy overlap |
| 8 | 80% | Hypertrophy |
| 10 | 75% | Hypertrophy |
| 12 | 70% | Hypertrophy, higher volume |
| 15 | 65% | Endurance, technique work |
Where the estimate stops being reliable
Accuracy falls off steeply as the rep count rises, and the reason is that a high-rep set stops being a test of strength and starts being a test of endurance, pain tolerance and cardiovascular fitness.
- Reliable (1–6)
- Usable (6–10)
- Rough (10–12)
- Unreliable (12–20)
| Category | Range |
|---|---|
| Reliable | 1 to 6 reps |
| Usable | 6 to 10 reps |
| Rough | 10 to 12 reps |
| Unreliable | 12 to 20 reps |
- The set must be genuinely near failure. A set of 5 with 3 reps left in the tank will underestimate your max substantially. Reps in reserve is the variable the equations cannot see.
- Technique has to hold. Reps that degrade into a different movement are not reps of the lift you are estimating.
- Lift-specific. Bench, squat and deadlift each have their own relationship between reps and percentage. Deadlifts in particular tend to produce fewer reps at a given percentage than the table suggests.
- Training status matters. Cummings and Finn found prediction accuracy in women changed measurably after a period of resistance training — the same person's rep-to-max relationship shifts as they train.3
Why you probably should not test a true 1RM
A maximal single is the highest-risk thing you can do in a gym, it requires technique that holds up under maximal load, and it leaves fatigue that costs you days of training. Unless you compete in a strength sport, the estimate is accurate enough to program from and free of all three costs.
Programming from the number
The %1RM table exists so you can choose loads deliberately rather than by feel. What decides your results, though, is volume — and the evidence on that is fairly clear.
- Pick a rep range for the goal. Strength lives at 1–6 reps (85–100%); hypertrophy across 6–12 (70–85%). The ranges overlap more than the tradition suggests.
- Count hard sets per muscle per week. Schoenfeld's dose-response meta-analysis found muscle growth increasing with weekly set volume, with roughly 10+ sets per muscle per week outperforming fewer.4
- Do not assume more is better for strength. A follow-up trial found higher volume increased hypertrophy but not strength in trained men.5 The two goals do not need the same dose.
- Progress the load, not the estimate. When a working set that used to be hard becomes easy, add weight. Recalculate from a real set rather than re-testing.
- Recalculate every 4–6 weeks from your best genuine set of 3–6.
Fuel it properly
Strength work in a large deficit is a bad trade. If you are dieting, keep the deficit moderate with the Calorie Calculator and protein high with the Protein Calculator — that combination is what preserves the strength you are building.
Terms used on this page
- 1RM
- One-repetition maximum — the heaviest weight you can lift once with acceptable technique. The reference point most strength programming is written against.
- RIR (reps in reserve)
- How many more reps you could have done. A set taken to 2 RIR stops two short of failure. The main uncontrolled variable in any 1RM estimate.
- Volume
- Total work done, usually counted as hard sets per muscle per week. The strongest driver of muscle growth, and a weaker one of strength.
- Autoregulation
- Adjusting the day's load to how you actually feel rather than to what the plan says. A practical answer to the fact that your true max moves day to day.
The formula
- Weight 100 kg, 5 reps
- Epley: 100 × (1 + 5/30) = 100 × 1.1667
- Brzycki: 100 × 36 / 32 = 112.5
Source: Epley & Brzycki. Published clinical/scientific formula.
Limitations
- Formulas degrade above ~10–12 reps; treat high-rep estimates as rough.
- They assume a controlled, full range of motion — sloppy reps overestimate your true 1RM.
References
- 1.Poundage chart. Epley, B., Boyd Epley Workout, University of Nebraska Body Enhancement Laboratory, 1985.
- 2.A new relationship between endurance and strength (the Brzycki equation). Brzycki, M., Journal of Physical Education, Recreation & Dance 64(1):88–90, 1993.
- 3.Accuracy of prediction equations for determining one repetition maximum bench press in women before and after resistance training. Cummings & Finn, Journal of Strength and Conditioning Research 12(4):262–265, 1998.
- 4.Dose-response relationship between weekly resistance training volume and increases in muscle mass. Schoenfeld, Ogborn & Krieger, Journal of Sports Sciences 35(11):1073–1082, 2017.
- 5.Resistance training volume enhances muscle hypertrophy but not strength in trained men. Schoenfeld et al., Medicine & Science in Sports & Exercise 51(1):94–103, 2019.
Frequently asked questions
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Read articleNot medical advice. This calculator is for general informational purposes only and is not a substitute for professional medical guidance. Always consult a qualified healthcare provider before making decisions about your health. Read the full medical disclaimer.
Printed from mystatura.com — for general information only, not medical advice.