Note: One Rep Max Calculator Below on this page
If you didn’t know already, your one rep max (1RM) is your one repetition maximum. In weight training/lifting, it’s the maximum amount of force that can be generated in one maximum contraction or, in other words, the heaviest weight you can lift once, correctly and completely.
For example, if you can bench press 100kg once, for one full repetition, and it’s not possible to do another full repetition, then your one rep max or 1RM is essentially 100kg. This can be a useful stat to track your progress and it’s often referenced in The Lean Exec training, although it’s not necessary to actually do it (unless you want to). In fact, arguably testing your 1RM can be dangerous, if you don’t do it correctly or safely. For example, if you overestimate your strength and try to lift a very heavy weight off the bench free weight rack, then can’t support it or find the strength to put it back on the rack, you could drop the heavy weight on your chest, causing serious damage.
We don’t want to deter you from trying it at all, just ensure you do it safely, using a capable training instructor or partner (spotter) who can help you if you get into trouble, or by applying the safety bars that are now available with most modern equipment. Ideally, you should do both, but if nothing else, it’s recommended you use the safety bars.
If you don’t fancy testing your 1RM just yet, or would rather not do it for any reason, there are other ways to check this stat with a lighter, more manageable weight. A quick search online will show there are lots of calculators available that will allow you to input a weight you can lift, say, 5 or 10 times, that will then give you a reasonably accurate estimate of your 1RM. There are also lots of gym mobile apps that allow you to input your lifting progress and estimate your 1RM and other useful stats, like volume of weight lifted automatically.