But beyond aesthetics, there's a real-world reason to turn on dark mode: increased battery life. According to a recent test, conducted by PhoneBuff, switching to dark mode can extend your iPhone's battery life by 30%.
In the test, identical tasks were performed on an iPhone XS Max in Twitter, YouTube, Message, and other apps, first with the phone running light mode, and then with dark mode on.
The result is quite spectacular. When the battery on the iPhone running light mode died, the other iPhone still had 30% battery life, which should give you several extra hours of service.
Things aren't that simple, though. The test phones were set to 200 nits of brightness; you might see different results with other settings. Furthermore, during the test a single app was used for several hours at a time, which is (hopefully) not how most users use their phones.
And there's a one big caveat: Only smartphones with OLED screens will see the battery life improvement. That’s because on OLED screens, black pixels are turned off instead of being backlit. So, users who are running an iPhone X, XS, XS Max, iPhone 11 Pro and iPhone 11 Pro Max will get the benefit. However, those with an iPhone XR and iPhone 11 won't get the benefits.