Re: The more I look at the more I believe the 400%/320px measure is near perfect.

Hi Wayne,

I think there are two fronts for education: one is developers, the other is users (and users who are developers!)

There is a lot of built-up habit for using text-sizing, and in every case I’ve seen so far using zoom would be better for the user.

Here’s one from this week:
https://twitter.com/stommepoes/status/937619495820161024 (scroll up for the discussion).

Getting something on Alistapart would be great, feel free to take points from my recent article:
https://alastairc.ac/2017/11/is-text-sizing-dead/


Are there good venues you know of for updating organisations that help people with low vision? A ‘train the trainers’ type article would be another good thing to get done.

Thanks,

-Alastair


From: Wayne Dick

Alastair really hit the mark with this calculation. Here is why I think so.

User Side
1. Each screen has an optimum viewing distance for each person. As Alastair points out, screen manufactures try to make the mean of these optimum distances be the distance at which 16px = 12pt. Where pixel is a screen relative measure, and point is an actual measure 1/72 inch.
2. A person with low vision does not have to view the screen from the mean optimum distance for normal readers. I usually view from about 2/3 that distance. The effect of my moving the screen to 2/3 distance is to increase the effective font size by 150% that is 450%. Of course cutting the distance in 1/2 with 400% gives a size increase of 800%. I have tried these distances and they both enable viewing the entire screen.

The net effect is that a point size of 12x8=96pt can be achieved with a person retaining a healthy posture.

Developer Point of View
1. Sizes can be computed in pixels without loss of generality.
2. The methods to achieve 320px good behavior are extremely well tested.
3. A large number of websites meet this goal already.

Maybe a few of us should combine this with some more good things about the number and publish it in A List Apart.

It might be a good way to sell the change.

Wayne