One-Rep Max Calculator
Estimate your one-rep max from any set using the Epley and Brzycki formulas, plus a full percentage chart for programming. Free 1RM calculator.
Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition of an exercise with good form. It's the reference point for serious strength programming — most training percentages (your working weights) are calculated from it. But actually testing a true 1RM is risky and fatiguing, especially for beginners.
This calculator estimates your 1RM from a set you've already done — say, 80 kg for 5 reps — using two of the most validated formulas (Epley and Brzycki), then averages them. It also prints a full percentage table so you instantly know what to load for any rep range.
Estimate your 1RM
| % of 1RM | Weight | Approx reps |
|---|
How to use the percentage table
Strength programmes prescribe loads as a percentage of your 1RM. For example, a classic strength block might call for sets of 5 at 80%, while a hypertrophy block lives around 65–75%. The table above does that maths for you — find the percentage your programme asks for and read off the weight.
| Training goal | Intensity | Typical reps |
|---|---|---|
| Maximal strength | 85–100% 1RM | 1–5 |
| Strength + size | 75–85% 1RM | 5–8 |
| Hypertrophy (size) | 65–75% 1RM | 8–12 |
| Muscular endurance | 50–65% 1RM | 15–20+ |
The fewer reps in your test set, the more accurate the estimate. A set of 2–5 reps gives a tight prediction; a set of 15 is more of a ballpark. Never chase a calculated number with poor form — and if you do attempt a true max, always use a spotter or safety arms.
Best lifts to test
The compound barbell lifts give the most meaningful 1RM numbers because they involve large muscle groups and are easy to load progressively: the back squat, deadlift, bench press and overhead press. Dial in technique first — a bigger, safer max is built on good positions. From there, drive it up over time with progressive overload.
Sources & further reading
- Epley B. "Poundage Chart." Boyd Epley Workout, 1985 — basis of the Epley 1RM formula.
- Brzycki M. "Strength testing — predicting a one-rep max from reps to fatigue." JOPERD. 1993.
- National Strength and Conditioning Association (NSCA) — Essentials of Strength Training and Conditioning, load–rep relationships.
External links are provided for reference and do not imply endorsement. arsenal.fit is an independent publisher and is not affiliated with any cited organisation.