One of my page make-up programs has a kerning feature that lets
me kern in 1/24 of an EM, while my other program lets me kern
in 1/100 of an EM. How can I arrive at a value for, let's say,
a 4 point kern? My point size is 12 point and I'm using the
24-Unit EM!
EQUATION:
12 pt type 24-Unit EM
----------- x ----------
4 pt. kern ?
Spoken: 12 pt type is to 4 pts of kern as
a 24-Unit EM is to how many units to kern
To solve for ? (our unit value), we cross-multiply 4 by 24 and then divide by 12. Enter the above equation into the Equation template, leaving the ? field blank. Click the Equal Button to solve the equation.
Now that we have solved for ?, we can solve for any value in the equation to check our work. Clear one of the values and hit the Equal Button. The number reappears. Presto!
Change the Em Unit Sys. field to calculate units in another EM Unit System.
CONSIDERATIONS: Since all programs won't allow fractions of an
EM unit, results of the calculation that are not
whole numbers will have to be rounded. Though
this does not solve the problem, it's as close
(short of changing your point size [just for the
kern] to one that will yield a whole number*),
as you can get. Whew!
*This can be accomplished using the same equation.