Alright math time.

A quick google comes up with this blog post, which I haven’t vetted or even read at all, it just has a table with some stats dodonut.com/blog/does-dark-mode-save-battery/

Apparently going to dark mode with 100% brightness provide a net saving of 40% on a pixel 2. Let’s assume this is universally true for all OLED and AMOLED displays, LCD users won’t see a difference, neither will CRTs but … I don’t think that I’ve heard of a CRT display on a phone.

40%? That sounds like a lot, doesn’t it?

Well yes and no, in relative terms it’s impressive, but it really depends on absolute terms. So how much does a phone use? The pixel 2 from before comes with a 10.39Wh battery, let’s assume you’re average use is 80% per day, then that comes out to 8.32Wh per day per phone. That means that the 40% reduction is 3.33Wh.

Is that a lot? Depends, if your only power source is a potato with a bit of copper and a galvanized nail, then yes, otherwise no.

Over the course of a year 3.33Wh a day comes to 1.215kWh annually.

Let’s put that into some context. The largest Vestas offshore wind turbine is the 15MW V236 www.vestas.com/en/products/offshore/V236-15MW. It can produce 80GWh annually. With the saving of 1.215kWh per phone, then for every approx 66 million OLED phones, we can skip erecting one offshore wind turbine.