We’ve known, for quite some time, that Dark Mode can dramatically reduce power consumption of the display panel if it is an OLED kind. Unfortunately it took Apple and Google a really long time to fully embrace Dark Mode in their operating systems, but now that it is here, you are free to try it out.

The folks over at PhoneBuff have put these claims to test to see exactly just how much longer will your battery last with Dark Mode on, opposed to using the regular, light interface. They’ve taken two identical iPhones, set up identically, with the same screen brightness. One with Dark Mode on, one standard, and, with the help of robots, they had them perform the same tasks.

At the end of the test run, they’ve concluded that when the iPhone with “light mode” on ran out of juice, the Dark Mode iPhone still had about 30% battery charge in it, which is rather huge. Check out the full video below!