About the one rep max calculator
Your one-rep max (1RM) is the most weight you can lift once with good form. Testing it directly is tiring and risky, so these formulas estimate it from a lighter set taken close to failure.
Use the percentage chart to plan working sets. Most strength programs use 70% to 85% of 1RM for sets of 3 to 10 reps.
Formula
Epley: 1RM = w × (1 + reps ÷ 30). Brzycki: 1RM = w × 36 ÷ (37 − reps). Lander: 1RM = 100 × w ÷ (101.3 − 2.67123 × reps).
Frequently asked questions
Which 1RM formula is the most accurate?
No formula is perfect. For low reps (2 to 6) they agree closely; for higher reps, estimates diverge, so the average is a reasonable choice.
Is it safe to test a true 1RM?
It carries more injury risk than lighter sets. Use a spotter or safeties, warm up well, or rely on the estimate instead.
These calculators give general estimates and are not medical advice. Talk to a doctor or registered dietitian before changing your diet or exercise routine.