One Rep Max (1RM)
Estimate your max single-rep lift from a sub-maximal set.
Find your max without maxing out
Your one-rep max (1RM) is the most weight you can lift for a single rep, and it's the reference point for most strength programming. Actually testing it is fatiguing and risky, so this calculator estimates it from a set you've already done — enter the weight and reps and pick the Epley or Brzycki formula.
You also get a full percentage table (95% down to 65%) so you can load the bar for any rep target. To put those numbers to work, read the 1RM & progressive overload guide, then use the plate calculator to load up.
Frequently asked questions
How is one rep max estimated?
The calculator uses validated formulas — Epley (weight × (1 + reps/30)) or Brzycki — to project your single-rep maximum from a set performed at a lighter weight for multiple reps.
How many reps give the most accurate 1RM estimate?
Accuracy is highest with sets under about 10 reps. The further past 10 reps you go, the more the estimate drifts, because fatigue and technique start to dominate.
Epley or Brzycki — which should I use?
They agree closely at low reps. Brzycki tends to give slightly lower estimates at higher reps. Epley is a solid default; pick one and stay consistent so your tracking is comparable.