How to calculate CSS letter-spacing v.s. “tracking” in typography?

Question

I have instructions from a graphic designer for a layout that specifies \"track 100\" for some elements. In CSS letter-spacing is the equivalent property for \"

Answer 1

For the most part the above answers are accurate enough, however, the 1000 that's being used assumes your font has an Em Size of 1000, and that's not always the case. I've seen fonts that have an Em Size of 1024, and some that were even 2048, which is obviously going to have an impact.

You can find out a font's Em Size by opening it inside of something like Font Forge and then selecting the Elements -> Font Info menu item, and the General tab.