One-Rep Max Calculator
Your one-rep max (1RM) is the most weight you can lift once. Instead of attempting a risky maximal lift, estimate it from a lighter set — enter the weight and reps to get your 1RM and a full percentage table.
One-Rep Max Calculator
Your one-rep max (1RM) is the most weight you can lift once. Instead of attempting a risky maximal lift, estimate it from a lighter set — enter the weight and reps to get your 1RM and a full percentage table.
- Brzycki estimate
- 90 kg
- 100% of 1RM
- 93.3 kg
- 95% of 1RM
- 88.7 kg
- 90% of 1RM
- 84 kg
- 85% of 1RM
- 79.3 kg
- 80% of 1RM
- 74.7 kg
- 75% of 1RM
- 70 kg
- 70% of 1RM
- 65.3 kg
- 65% of 1RM
- 60.7 kg
- 60% of 1RM
- 56 kg
- 55% of 1RM
- 51.3 kg
- 50% of 1RM
- 46.7 kg
Epley: weight × (1 + reps ÷ 30). Brzycki: weight × 36 ÷ (37 − reps). Most accurate at 10 reps or fewer.
This is an educational estimate, not medical advice. Consult a qualified professional.
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How your 1RM is estimated
This calculator uses two of the most validated formulas. Epley: 1RM = weight × (1 + reps ÷ 30). Brzycki: 1RM = weight × 36 ÷ (37 − reps). Both convert a "reps to failure" set into an estimated single-rep maximum.
The two formulas agree closely at low reps and diverge a little as reps climb. Accuracy is best when your set is 10 reps or fewer — beyond that, factors like muscular endurance muddy the estimate. For the most reliable number, use a hard set of 3–6 reps.
Training with percentages of your 1RM
Most strength programs prescribe loads as a percentage of 1RM, which is why the table above matters. As a rough guide: 85–100% builds maximal strength (1–5 reps), 70–85% builds muscle (6–12 reps), and 50–70% develops muscular endurance (12+ reps).
Knowing your 1RM lets you pick the right weight for the goal of each session and progress in a structured way, rather than guessing. Recalculate every few weeks as you get stronger.
Lifting safely
An estimated 1RM is a planning tool, not a target to chase recklessly. True maximal attempts carry real injury risk and should only be done with proper warm-up, good technique and a spotter — which is exactly why estimating from a submaximal set is so useful.
Always warm up thoroughly, keep your form strict, and increase load gradually. If a weight feels wrong, stop. Beginners in particular gain plenty from moderate weights and don’t need to test true maxes.
Train your lifts safely
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Frequently asked questions
What is a one-rep max?
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 standard benchmark for maximal strength.
Which is better, Epley or Brzycki?
Both are well validated and agree closely at low reps. Epley tends to read slightly higher at higher reps. Using a set of 5 reps or fewer makes both more accurate.
How often should I recalculate my 1RM?
Every four to six weeks, or whenever your working weights climb noticeably. Re-estimating keeps your training percentages accurate as you get stronger.
Sources & references
- Brzycki M. "Strength testing — predicting a one-rep max from reps-to-fatigue." JOPERD. 1993;64(1):88–90.
- LeSuer DA, McCormick JH, Mayhew JL, et al. "The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift." J Strength Cond Res. 1997;11(4):211–213.
Not medical advice. This result is an educational estimate from HealthyLifeStyles (Trusted Wellness), based on population formulas — not a diagnosis or treatment. Always consult a qualified healthcare professional about your health.
https://www.healthylifestyles.com/tools/one-rep-max-calculator