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One rep max calculator: estimate your 1RM
Enter the weight and reps from any working set to get your estimated one rep max, plus a full percentage table for programming your training.
One rep max calculator
Your estimated 1RM
Average of Brzycki, Epley and Lombardi formulas
| % of 1RM | Weight (kg) | Approx reps |
|---|---|---|
| 100% | 92.4 kg | 1 |
| 95% | 87.8 kg | 2 |
| 90% | 83.2 kg | 4 |
| 85% | 78.6 kg | 5 |
| 80% | 73.9 kg | 6 |
| 75% | 69.3 kg | 8 |
| 70% | 64.7 kg | 10 |
| 65% | 60.1 kg | 12 |
| 60% | 55.5 kg | 15 |
About this tool
What a one rep max is — and why you need to know it
Your one rep max (1RM) is the maximum weight you can lift for a single repetition with correct form. It is the standard measure of absolute strength in powerlifting and strength training, and it is the basis for almost all percentage-based programming (5×5, 5/3/1, conjugate, etc).
Testing your true 1RM carries injury risk — this calculator estimates it from a sub-maximal effort using three established prediction equations, then generates the full percentage table so you can programme your training immediately.
Step by step
How to use the one rep max calculator
- 1
Enter the weight you used for your working set
Use the weight you actually lifted — not a planned or target weight.
- 2
Enter the number of reps you completed (up to 10)
Accuracy drops above 10 reps. For best results use a set of 3–6.
- 3
Your estimated 1RM and full percentage table appear instantly
Use the table directly for programming your next training block.
Methodology
The three formulas
| Formula | Equation | Notes |
|---|---|---|
| Brzycki (1993) | 1RM = weight ÷ (1.0278 − 0.0278 × reps) | Tends to be slightly conservative |
| Epley (1985) | 1RM = weight × (1 + reps ÷ 30) | Widely used in sports science |
| Lombardi (1989) | 1RM = weight × reps^0.1 | Tends to produce slightly higher estimates |
The calculator shows the average of all three formulas.
Worked example
Example calculation
Brzycki: 80 ÷ (1.0278 − 0.139) = 80 ÷ 0.889 ≈ 90.0 kg. Epley: 80 × 1.167 ≈ 93.3 kg. Lombardi: 80 × 5^0.1 ≈ 86.5 kg. Average ≈ 89.9 kg.
Be aware
Assumptions and limitations
- Accuracy decreases above approximately 10 reps; best results come from 1–6 rep sets.
- Assumes consistent technique — a fatigued or sloppy set will underestimate your true 1RM.
- Not suitable for Olympic lifts (snatch, clean and jerk) where technique is the primary limiting factor.
Questions
Frequently asked questions
How accurate is this estimate?
For 1–6 reps from a quality set, the typical margin of error is 2–5%. For higher rep sets, it widens. Track your estimated 1RM over time even if you never test the real thing — the trend is what matters.
What rep range should I use for the best estimate?
3–6 reps on a moderately heavy set gives the most consistent estimates across all three formulas. A single set to failure works; a set stopped a rep or two short will underestimate your true 1RM.
How do I use the percentage table?
Most percentage-based programmes (5/3/1, Juggernaut, etc.) prescribe work at 65–95% of 1RM. Find your weight for those percentages in the table and use them directly as your working weights.
What is a good one rep max for bench press?
Benchmarks vary by bodyweight and training experience. As a general guide for men: beginner — bodyweight; intermediate — 1.25× bodyweight; advanced — 1.5× bodyweight or more. For women: beginner — 0.5× bodyweight; intermediate — 0.75× bodyweight; advanced — 1× bodyweight. These are rough population norms, not personal goals — your own progress over time is the more useful measure.
How do I safely test my one rep max?
Warm up thoroughly: 5–10 minutes light cardio, then progressive warm-up sets (50%, 70%, 85%, 95% of expected 1RM, with 2–3 minute rest between). Have a spotter for compound lifts. Stop if form breaks down — a true 1RM should be heavy but technically clean. Rest 3–5 minutes between attempts. For most training purposes, a predicted 1RM from a 3–5 rep sub-maximal set is safer and accurate enough.
Estimates, not medical advice
FitnessCalculator.info provides general health information for educational purposes only and does not replace advice from a qualified coach or healthcare professional.