Conversion rate of pt, em, px, percent, other

Question

More so than less I run into times when I need to use pt instead of px or em instead of pt, or whatever the case, and trying to find the right size for something bigger than

Answer 1

Well,

12pt = 16px = 1em = 100%

assuming you don't change the font size on the body (else the pt will be different), the dpi of your OS is set at 72 etc etc..

The relationship looks like:

pt = 3/4*px

em = pt/12

% = pt*100/12

in this case. It's worth pointing out that using pt is wrong, unless you are printing something, and that using px, % or em is more usual.

Personally, I just use px or em. Using % or em is handy for designs where the base font size changes for smaller screens.