The SixPackSmackdown.com bench press calculator can be used to estimate 1 rep max bench press or squat. These figures are not 100% accurate, but it serves as a good starting point as some routines (like a bench press pyramid) are based off of your 1RM.
This bench press calculator can be used to estimate 1 rep max bench press or squat. The way this bench calculator works is it takes the amount of weight you can bench for a certain number of reps, multiplies it by a standard coefficient and then outputs your approximate 1RM. Obviously, these figures are not 100% accurate.
To use the bench press calculator simply enter the weight you are bench pressing (or squatting) and then select the number of reps from the list box. Your max will be automatically generated.