Pixels are dying. Or rather, they’re riding off into the sunset. Retinal display is the thing, and today’s 1080p is tomorrow’s 640×480.

So as designers, we should stop designing in pixels, completely. We should start using points instead.

% and em are great, but they’re relative. So if you tell me something is 1 em wide, I have no idea how big that is. That’s why pixels are popular; they’re absolute. I have a clear idea as to how big a website is if it’s 960 px wide.

Or do I? In fact, px is a relative unit of measurement. It’s relative to the pixel density on the screen. And on a retinal display, pixels are theoretically invisible.

Print never had to deal with all this. Printers have always been able to render insanely small dots-much finer than the latest retinal screens can. Which is why points, or 1/72 of an inch, have always held sway. That and their older siblings, picas, or 12 points, or 1/6″ of an inch.

A point is a point is a point. If a website is 720 points wide, it’s 10″ wide. Period. And any device that renders it can check with its own screen density settings to figure out how many pixels it should use to render that site.

It would be great to see more designers using points and picas in their css. Of course, basing those units on a percentage of a centimeter instead of an inch would make even more sense, but it’s probably too late for that.