Neil Hughes ran some battery tests on the iPhone X comparing standard white-background UIs against the “dark mode” generated by iOS 11’s Smart Invert Colors in Safari. The results are remarkable:

Reddit normally features a white background and black text, but with Apple’s smart invert colors option enabled, the back of the screen is now black and the text is white. This is important because black pixels in an OLED are essentially “turned off” and consume far less power — a stark contrast from LCD displays, where the backlight must illuminate all pixels, including black ones.

After three hours with maximum brightness and smart invert colors enabled, the iPhone X battery dropped from 100 percent to just 85 percent.

We then ran the exact same test with an iPhone X running in normal mode — that is to say, Reddit was loaded on Safari with a white background and black test. With the backlight turned up to maximum, the battery drained from 100 percent down to 28 percent.

It’s an extreme comparison, but it proves how dark interfaces could be marketed as beneficial for the iPhone X’s battery life. I wonder if the long-awaited system-wide iOS dark mode could be presented as an energy efficiency feature next year?

(Related: as we mentioned on last week’s Connected, if you have an iPhone app with a custom dark mode, you’ll want to update it so it offers a “pure black” option on the iPhone X. It looks so much better than gray or dark blue.)