Your set
While you’re here — claim a crypto exchange bonus
Bonuses you get just for signing up. Terms are copied straight from each exchange.
Estimating beats testing
A one-rep max is the heaviest weight you can lift once. Testing it means grinding to failure, which carries real injury risk and costs days of recovery. Working backwards from a set you already did — five reps at a given weight is plenty — is safer and accurate enough for programming.
The formulas disagree, on purpose
Epley, Brzycki and Lombardi come from different datasets, so the same input can produce estimates several kilos apart. Showing one number makes it look definitive. This calculator shows all three, takes the middle value as the recommendation, and reports the spread so you can see how confident to be.
What you actually use is the percentage table
Programmes are written as "80% of 1RM for five sets of five". The table below converts your estimate into working weights rounded to 2.5 kg, which is the plate increment, so the number on screen is the number you load.
More calculators
Frequently asked questions
QShould I test my 1RM directly?
Generally no. A true single means grinding to failure, with real injury risk and several days of recovery. A set of five to eight reps gives an estimate that is safe to collect and accurate enough to programme from.
QWhich formula is correct?
None of them, exactly. They are regressions on different populations, so they disagree by a few kilos on the same input. Using the middle of the three, and watching the spread, is more honest than picking a favourite.
QHow many reps give the best estimate?
Five to eight. Above ten reps the formulas diverge sharply, because endurance starts to dominate. Below three you are already close to a true max, so there is little left to estimate.
QWhy round to 2.5 kg?
Because that is the smallest plate pair on most bars. A calculation of 78.3 kg cannot be loaded; 77.5 or 80 can. The table gives you what you can actually put on the bar.
QDoes this work in pounds?
The formulas are unit-free, so an input in pounds gives an output in pounds. Only the 2.5 kg rounding is metric — in a pound gym, round to the nearest 5 lb yourself.