I guess I can understand why – changing the way you use your MacBook can change how much battery life it has left in seconds. Also: How to replace the battery in your MacBook or MacBook Pro But I must admit, getting an idea of how long the battery might last based on current workloads can be quite useful. As long as that figure is somewhere in the right ballpark. A tool that can tell you this, plus a lot more, is iStat Menus by Bjango. If all iStat Menus did was tell me how long my battery is going to last, the $9.99 price tag might seem a little bit steep, but this one app does so much more. This one app shows CPU, GPU, and memory usage, how much data is being sent and received over the networks the Mac is connected to, disk usage and activity, what’s being reported by sensors monitoring temperature, fan speed, voltage, current, and much more, and everything you need to know about the battery and power systems. And another superb feature is that everything is customizable, so whether you’re someone who wants to know everything, or someone who just wants the information they need, you can set iStat Menus to work the way you work. Normally, apps that display a lot of data are ugly and chaotic. Not this app. This is an app that I’d call beautiful, and there are colors and themes to suit all tastes. I use this app often and, I have to admit, one bit of information I go looking at regularly is how much battery life I have left. It’s handy to know if I should take a charger with me when going out and about, and I’ve been really impressed by the accuracy of this figure. I’ve been using iStat Menus for years now, and I’ve watched this app get better and, with support for new Macs, along with new features, being added regularly. There’s a 14-day free trial of iStat Menus available (which is more than enough time to fall in love with this app), and after that a single license costs $11.99, and a 5-Mac family Pack is $14.99.