One-rep max calculator

Every rep-max formula is a curve fitted to a group of people, then applied to you. They agree closely at three to five reps, which is what they were built on, and drift apart fast above ten — by twelve reps the spread between the highest and lowest estimate is routinely 10%.

So the honest output is a range. If four formulas say 110 to 118 kg, your max is somewhere in there, and the way to find out precisely is to work up to it under a spotter, not to trust a page.