How to use the One Rep Max Calculator
- Enter the weight you lifted and how many full reps you completed (1–12 reps gives the best estimate).
- Read your estimated one-rep max — the average of seven well-known formulas.
- Use the percentage table to plan training sets.
- Optional: use the independent plate loader for a load you choose.
How is one-rep max estimated?
Lifting your true maximum is tiring and carries injury risk, so coaches estimate it from a heavier set of several reps. The most common formula is Epley: 1RM = weight × (1 + reps ÷ 30). For 100 kg × 5 reps that is 116.7 kg. Brzycki (weight × 36 ÷ (37 − reps)) gives 112.5 kg. Formulas agree closely at low reps and drift apart above about 10 reps, so the calculator shows them all and uses the average.
Training percentages
- 90–100% of 1RM: 1–3 reps — maximal strength.
- 80–90%: 3–6 reps — strength.
- 65–80%: 6–12 reps — hypertrophy (muscle size).
- Below 65%: 12+ reps — muscular endurance, technique and warm-ups.
Getting a reliable estimate
Use a set taken close to failure with good form, ideally 3–8 reps, done when fresh. Estimates are least accurate for very high reps and for beginners whose technique is still improving. Always use a spotter or safety bars for heavy bench press and squats.
Frequently asked questions
What is a good bench press 1RM?
It depends on body weight, age and training history. Benching around your body weight is a common intermediate milestone for men; around 0.6–0.7× body weight for women.
Which 1RM formula is most accurate?
Epley and Brzycki are the most widely used and are accurate below about 10 reps. Averaging several formulas smooths out their differences.
How often should I test my 1RM?
Most programs re-test or re-estimate every 4–12 weeks.