Unit of letter spacing and line height

[ucmb46763466]

I handed off my design to the developers and they were wondering what unit the letter spacing and line height have.

I am handing off my designs with the XD "for developers" feature.

Thanks for helping

[Peter Villevoye · Accepted solution]

It's in fractions of 1/1000 of the font size.

So 1000 would equal the size of the font.

Note: not the line height ! That's in points.

Units for Character spacing

There's some debate about whether it's equal or just similar to the "em" from the metal type era, since the CSS technologies (for the web) have declared an "em" as the font size. Wikipedia: Em (typography) While in old printer's jargon an "em" stands for a piece of lead type at the width of the capital M (hence "em" and it's half-sized brother "en").

Thomas Phinney (who also worked for Adobe) has a nice article about it:

Phinney on Fonts » Point Size and the Em Square: Not What People Think

[Guest]

I didn't know that I needed a calculator to use this programm...If adobe wants to make a better user experience for their users please change this to pixels, no one understands this system! For type / font systems styleguides this is a horrible user experience! Lately they just released "marketing features" for new users, instead of focusing in the users that use this professionaly...

[Feedsy Pty Ltd]

Line height should be able to be specified as a % (eg 120%) or Factor (eg 1.2). Not just an absolute px (eg 12px). Just like the web!

Am I missing something in XD?

Why doesn't Adobe take notice of their own Forums for this feature: https://adobexd.uservoice.com/forums/353007-adobe-xd-feature-requests/suggestions/13813872-line-heig...