Your estimated 1RM,with everything they leave out.
All seven classic formulas at once, the spread between them, which one the evidence backs for the lift you did, and how much the error in the number you typed weighs. Which is usually more than the formula.
112,5 kgestimated 1RM
The applicable formulas give between 112,5 kg and 119 kg.
What the evidence backs for this lift
- Lombardi (1989)117,5 kg
- Mayhew et al. (1992)119 kg
- Wathan (1994)116,6 kg
If the weight you entered were off by 2.5 kg, the result would shift 2,8 kg. The error in your input weighs more than the choice of formula — Reynolds and colleagues measured it in 2006.
Why seven and not one
Because there's no winner. Reynolds and colleagues validated all of them against actually measured 1RMs and the differences between them came in under one kilo of standard error.
The important finding in that work isn't which one wins: it's that the measurement error in your input dominates the result. A 5 kg error in a 5RM produces roughly 20 kg of error in the estimated leg press 1RM.
Picking one formula and presenting its output as “your 1RM” hides that. Showing all seven and their spread shows what's actually known.
Which to use, per what each study measured
- LeSuer and colleagues (1997), 67 untrained college students: Mayhew and Wathan were the most accurate, only Wathan predicted the squat well, and all seven underestimated the deadlift.
- Wood and colleagues (2002), 49 sedentary adults: Wathan, Epley and Mayhew at 12 to 23 % error. Lander was catastrophic: 76 to 157 %.
- Ribeiro and colleagues (2024), 119 people after 16 weeks of training: in men, Lombardi was the most accurate for bench and squat; in women, Brzycki and Lander for those same lifts.
Why it doesn't ask your sex or training level
Because it doesn't change the result, and there's a large meta-analysis that measured exactly that.
Nuzzo and colleagues reviewed 269 studies covering 7,289 people in 2023, looking for precisely this: whether sex, age or training status moderate the relationship between reps and percentage of 1RM. They didn't find that they clearly do.
What they did find is that the exercise matters, a lot: at 80 % of 1RM, people manage 13.1 reps on the leg press against 8.8 on the bench press. That's why this calculator asks what you lifted, not who you are.
A calculator offering a “formula for women” or a “formula for advanced lifters” is selling a precision the aggregate evidence doesn't support.
The formulas that break
Brzycki and Lander have a denominator that hits zero: with 100 kg at 40 reps, Brzycki returns −1,200 kg and Lander −48,370.
This isn't a theoretical case: anyone can type 40 reps into a calculator. Here those formulas are flagged as out of range before they get there, instead of showing an impossible number to two decimals.
And one clarification almost nobody makes: “Baechle” is Epley. The 0.033 constant is 1/30 rounded. Calculators offering them as two separate options are offering the same function twice.
Myosin works it out on every set
Here you have to type the weight and the reps. In the app, estimated 1RM comes from every set you log, per exercise, and builds the curve over time — so you can see whether you're progressing without ever attempting a true max.
