1rm.io is a free online tool for calculating your 1RM (1 Rep Max). It's brought to you by the folks who make Leadrbox*, a software company focused on bettering the lives of athletes and trainers through technology.
1RM calculators are used to predict a one rep maximum. 1RM is the amount of weight an athelete can lift cleanly, with solid form from begining to end. Performing an actual 1RM can be dangerous for a number of reasons (not the least of which is injury). For most athletes it is safer to do less than their 1RM weight for as many repetitions as they can with good, clean form. Then use those values with a 1RM calculator to predict ones actual 1RM.
* Leadrbox is an application for trainers, atheletes, teams and organizations to be more effecient, competitive and social with their workout progressions and overall progress. Is is currently in private alpha. Want to know more, contact us at email@example.com