One Rep Max Calculator
Know your one rep max without ever testing one.
Enter a weight and the reps you managed. Get an estimated 1RM averaged across seven formulas, the percentage table you actually train off, and the plates to load for every one of them.
Estimate instead of testing
Testing a true one rep max is taxing, needs a spotter, and is only accurate on the day you do it. A hard set of three to five gives you a number that is nearly as useful and costs you nothing. Since most programs are written as percentages of a max, that estimate is the number you actually need.
Enter the weight, the reps, and optionally how hard the set felt. You get the estimate and the whole rep max table underneath it.
- Estimate a 1RM from any weight, rep count, and RPE
- Seven formulas averaged, or pick the ones you trust
- Rep max table from 2RM to 11RM for programming
- Plate breakdown, rounded to a weight the bar can hold
- Per exercise history with your current and best 1RM
- Goals with a target date and progress to it
Seven formulas, not one opinion
Epley, Brzycki, Lombardi, Mayhew, McGlothin, O'Conner, and Wathan all estimate the same thing and all disagree, sometimes by several percent. Rather than pick one silently, the app averages them, and you can switch any of them off if you prefer a particular one.
If you want the math behind them, the guide to calculating a one rep max works through the equations and where they diverge, and our one rep max calculator runs all seven in the browser if you want to try it before installing anything.
The weight you can actually load
A percentage table that tells you to lift 247.3 pounds is no use standing at the bar. Every percentage comes with the plates to put on each side and the nearest weight your plates can actually make.
It handles pounds or kilos, and you can tell it which plates you own so it never suggests a pair you do not have.
Every lift in one place
Squat, bench, deadlift, press, or anything else you want to track. Each exercise keeps its current estimate next to your best one, so you can see at a glance which lifts are moving and which have stalled.
Watch the estimate climb
One estimate is a snapshot. A year of them is the only honest answer to whether your training is working.
Every logged set is plotted, so a lift that is creeping up and a lift that has been flat since spring look completely different at a glance.
Give yourself a number to chase
Set a target max and a date, and the app tracks the gap: how much you have added, how much is left, and the rate you need to hold to get there.
Once you have a max you trust, the 5/3/1 app will build a full training cycle from it.
Common questions
How many reps should I use for the best estimate?
Which formula is most accurate?
What does the RPE field do?
Do I need to test a real max to use this?
Does it work in kilos?
Why is the suggested weight not exactly the percentage?