Calculate your one-rep maximum using the Epley formula by multiplying 0.0333 by the number of bench press reps you can perform at a specific weight, adding 1, then multiplying the result by the specific weight. For example, if you can bench 200 pounds 10 times, then: 1 + (10 x 0.0333) = 1.333, giving you a one-rep max of 200 x 1.333 = 266.6 pounds.
Determine your one-rep max using a formula created by Matt Brzycki for the book, “A Practical Approach to Strength Training.” Perform one set of bench presses, using a weight you can lift no more than 12 times. Do the set to failure, then look up the result on Brzycki’s chart. If you can only do one rep, that weight is obviously your one-rep max. If you can perform 12 reps, then the weight you’re pressing is 70 percent of your one-rep max. If you lift 200 pounds 12 times, for example, divide 200 by 0.7, for a one-rep max of 285.7 pounds. The book “Strength Training Past 50” extends the chart beyond 12 reps, stating that 14 repetitions at a specific weight represents 65 percent of your one-rep max, while 16 reps equals 60 percent.
Choose the percentage of your one-rep max to lift during each set, based on your fitness goals. If you’re trying to build muscular endurance, powerlifting champion Curtis Dennis Jr. says to press 50 to 60 percent of your one-rep max while performing a high number of reps. If you’re moving up to a muscle-building program, lift 60 to 80 percent. If you’re training for a competition or you’re a serious bodybuilder, Dennis recommends lifting at least 85 percent of your one-rep max. Alternatively, the American Council on Exercise advises anyone seeking to build strength to perform three to five sets each of several compound exercises -- including bench presses -- while lifting 75 to 85 percent of your one-rep max.