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Pixels vs points / contrast ratios


From: Karl Brown
Date: Oct 10, 2017 4:57AM

Hi all,

I think there's been a lot of discussion about this before, but I wanted to
check my understanding of what "large scale text" translates as according
to the guidelines:

“The actual size of the character that a user sees is dependent both on the
author-defined size and the user’s display or user-agent settings. For many
mainstream fonts, 14 and 18 point [pt] is roughly equivalent to 1.2 or 1.5
em or 120% or 150% of the default size for body text (assuming that the
body font is 100%), but authors would need to check this for the particular
fonts in use”

Am I right in assuming that large scale bold text would be 14x1.2 (16.8
pixels) and large scale non-bold would be 18x1.5 (27 pixels)?

I have a lot of designers asking if they can use colour combinations at
3.1:1 and not liking when I suggest 4.5:1, so if there is an actual formula
we can use that'd help. Is the one from the guidelines suitable?

For this I'm ignoring the design considerations on whether or not the font
size looks good aesthetically, I'm more focused on translating pt units to

Karl Brown
Twitter: @kbdevelops
Skype: kbdevelopment

Professional Certificate Web Accessibility Compliance (Distinction),
University of South Australia, 2015