I use estimated rep and weight calculations multiple times a week in the gym and when planning out my training for the week. Some of the calculators out there are better than others. I’ve been using the one from All Things Gym for about a year, but I knew I could improve it. Since the author released all of the code on CodePen, I did just that.

I’ve improved the code to create my version of a rep max calculator and bought an obvious domain name – repmaxcalculator.com. Most of the time when I need an estimate I’m on my phone, so it was important for this to have a good mobile experience, which I think I’ve accomplished. If you’re using an iPhone, save it to your home screen so it launches just like an app, not in another Safari tab.

Try it out and let me know what you think. I’ve love to hear suggestions on ways it could be better.