One Rep Max Calculator
What is my one rep max?
If you bench 225 lb for 5 reps, your estimated one rep max is about 258 lb — 262.5 lb by the Epley formula and 253.1 lb by Brzycki.
Result
Estimated 1RM (average of both formulas)
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- Epley
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- Brzycki
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Above 10 reps, the estimate can be well off.
1RM percentage chart
| % of 1RM | Weight | Reps (approx.) | Typical use |
|---|
Something off with the result?
How it's calculated
Epley (1985) · Brzycki (1993)
- Epley: weight × (1 + reps ÷ 30)
- Brzycki: weight × 36 ÷ (37 − reps)
- At 1 rep, the weight lifted is your 1RM. The headline number is the average of the two formulas
- Chart reps come from solving Epley in reverse: 30 × (100 ÷ % − 1). Chart weights are rounded down to the plate step you pick
- 1 kg = 2.20462 lb
Frequently asked questions
How do you calculate your one rep max?
Take a weight you can lift for a few clean reps and plug it into a formula. With the Epley formula, 1RM = weight × (1 + reps ÷ 30), so 225 lb for 5 reps works out to 262.5 lb. The Brzycki formula, weight × 36 ÷ (37 − reps), gives 253.1 lb. This calculator shows both and their average.
Which 1RM formula is most accurate?
No single formula wins for everyone. Epley and Brzycki agree closely at low reps and drift apart as reps go up, with Epley reading higher. Averaging them is a sensible middle ground. Your true max also depends on the lift, your training and how fresh you are.
How many reps should I use to estimate my max?
Estimates are most reliable with 10 reps or fewer, and best around 3 to 8 hard reps with good form. Past 10 reps, muscular endurance starts to dominate and the estimate can be far off.
What percentage of my 1RM should I lift?
A common guide: about 85–95% for 2–5 reps when training for strength, 65–85% for 6–12 reps for muscle growth, and below 65% for higher-rep endurance or technique work. The chart above lists the weight at each percentage and roughly how many reps you can expect.
Is it safe to test a true one rep max?
A true max attempt carries more injury risk than any other set, so use a spotter or safety bars and warm up thoroughly. Estimating from a 3–5 rep set is a safer way to track progress between tests.