How to use the one rep max calculator
- Do a set of any lift — bench press, squat, deadlift, overhead press — with good form, ideally 3 to 8 reps close to failure.
- Enter the weight and the number of reps you completed.
- See your estimated one rep max (1RM) and a chart of training weights at each percentage.
One rep max formulas
Example: bench pressing 225 lb for 5 reps gives an Epley estimate of 225 × (1 + 5/30) = 262.5 lb. Brzycki gives 253.1 lb and Lombardi 264.3 lb. The formulas agree closely at low reps and drift apart as reps increase.
Using percentages of your 1RM
| Training goal | % of 1RM | Reps per set |
|---|---|---|
| Maximal strength | 85%–100% | 1–5 |
| Muscle growth (hypertrophy) | 65%–85% | 6–12 |
| Muscular endurance | 50%–65% | 12–20+ |
| Speed and power work | 30%–60% | 1–5, fast |
Many training programs (5/3/1, Starting Strength progressions, Texas Method) prescribe weights as a percentage of your 1RM — the table in the results does the math for you.
Why estimate instead of testing?
A true one-rep max test is fatiguing and carries more injury risk, especially for beginners. A rep-max estimate from a set of 3–8 reps is usually within about 5% of a tested max, and you can repeat it every few weeks to track progress. Estimates become less reliable above 10 reps and vary between people with different muscle fiber types.
Safety tips
- Warm up thoroughly with lighter sets before any heavy set.
- Use a spotter or safety bars for bench press and squats.
- Count only reps done with full range of motion and good form.
Frequently asked questions
How do I calculate my one rep max?
Lift a weight for as many good reps as you can (ideally 3 to 8), then use a formula such as Epley: weight × (1 + reps ÷ 30). 200 lb for 6 reps gives an estimated 1RM of 240 lb.
Which 1RM formula is most accurate?
Epley and Brzycki are the most widely used and are similar for sets of up to about 10 reps. No formula is perfect for everyone, so use the same one consistently to track progress.
What percentage of 1RM should I train at?
Roughly 85% or more for strength (1–5 reps), 65%–85% for muscle growth (6–12 reps) and below 65% for endurance work.
How many reps can I do at 80% of my max?
Most people can do about 8 reps at 80% of their one rep max, although this varies by person and exercise.
Does this work for squats and deadlifts?
Yes. The formulas apply to any multi-joint lift. They tend to be less accurate for small isolation exercises and machines.
This calculator provides general information only and is not a substitute for professional medical advice, diagnosis or treatment. Always consult a doctor or other qualified health provider about your individual situation.
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