When I first got the retina MacBook, the battery was 5297 mAh out of the box. The maximum battery now is 95% of that at 5028 mAh in less than a week. I have calibrated it once without any improvement, rather it is getting lower each day. I've kept it on its charger (through Apple USBC-HDMI-USB dongle) the whole time other than 1 calibration, despite it showing 4 cycles (it came out of the box with 3 cycles). If you download the free 'Battery Health' app from the App Store or 'Coconut Battery' from the web, those are a few methods to test your battery health. FYI: 12" Retina MacBook / Gold / 512GB / 1.2 Ghz. I look forward to comparing results.