MaxLift - 1RM Calculator app for iPhone and iPad

Your 1RM is the absolute maximum amount that you can lift for one rep of any given exercise. A true 1RM will leave you with nothing in the tank. You’ll have the internal feeling of, “I couldn’t add more weight to the bar if I tried.”

Technically, you can find your 1RM for any movement, not just compound exercises and big competition lifts. However, while you could find your 1RM for, say, barbell curls, it’s worth noting that not all 1RMs will carry the same weight when it comes to directing strategic programming.

Plus, maxing out with smaller, more vulnerable muscle groups may increase injury risk while eating into recovery. That may prevent you from getting stronger overall with bigger compound lifts. In that way, some exercises are simply not worth maxing out due to the risk:reward ratio that comes along with them.

When considering which lifts to determine your max for, think about your competition lifts. For weightlifters, that will be the snatch and the clean & jerk. For powerlifters (and sometimes strongmen and CrossFitters), it’s going to be the squat, bench press, and deadlift. Strongman and strongwoman athletes might also need to know their log press max, which you can also generalize into learning your overhead press 1RM.

HOW DO I TEST MY ONE-REP MAX?
Trainers and coaches often set up programs with percentages based on your one-rep max (1RM) because they dont know your actual strength level, but they know what percentages they want you to be using relative to your 1RM. Here are some important caveats to remember when using them:

The lower the number of reps you enter in, the more accurate your 1RM will be. In other words, a three-rep max (3RM) will give you a better estimate than a 12RM.
Stop your set once your form is at risk of breaking down, or your range of motion is decreasing. No 1RM is worth getting injured and having to stop training.
Remember that each exercise has its own 1RM. Dont use your back squat 1RM to compute your front squat. Strength is specific!