Why are computer pixels square?

As a designer primarily involved in creating experiences that exist in the form of pixels, this topic has forever interested me.

I’ve never been able to come up with a precise answer, I have however accumulated an interesting list of assumptions which could have informed the decisions of computer manufactures to opt for a 1:1 pixel aspect ratio, or PAR.

When computers first gained popularity as a consumer device, they were designed to be used with standard television sets. These sets varied in size and specification. It seems logical that computer manufactures wanted to focus on the computer first, before the display. People already had television sets in their houses, so why not use those? A typically smart move, by smart tech companies trying to establish an MVP as soon as possible.

Fast forward a few years and computers were selling like hot cakes, people were using them and people were loving them. They were here to stay, and this is where it gets interesting.

Dad was always using his TRS-80 right around the time mom wanted to watch Dallas, or maybe it was the other way around, maybe Mom always wanted to use the TV right when dad was trying not to be eaten by a grue. There you had it, social proof that people needed an extra screen.

By now computers were increasingly capable of dealing with the details of a graphical user interface. The computer industry needed to reach a consensus or a standard on the kind of monitors that would be put in production so that software developers could adequately anticipate the visual experiences they were building.

Take one example, the core of communication; Typography. It’s far easier to design, draw and control a font on a 1:1 pixel grid than it is on a rectangular grid. In fact, as 1:1 is the lowest common denominator it provides the highest level of fidelity when designing an interface. This, I believe is the strongest argument for why pixels are square.

Another idea is that computer monitors use the RGB colour model, which is similar to the way the human visual system works. RGB colour is often demonstrated as a cube, with each colour pertaining to a coordinate XYZ. I’m not sure what correlation that has to the 1:1 PAR, but it just seems to fit nicely.

This was an answer I posted on Quora