Text Areas and Font Sizes

Hey guys.

Working on a project right now and I’d like to make a certain aspect of it as flexible as possible. Basically here’s the scoop.
[LIST]
[]We have a bunch of text areas but we’ll focus on one
[
]User fills out input text area (Font size 11 pt, multiline text area but we only want 1 line to be filled out)
[]On submit I check the height of the text area (If the height is greater then the equivalent to one line I throw and error message - we don’t want to use character count)
[
]If all is ok the input the user typed goes into a dynamic text area for display(Font size 26)[/LIST]What I would love to do here is basically fill out a few variables

for example
ActionScript Code:
[FONT=Courier New][LEFT]dynamic_txt_font_size = [COLOR=#000080]26[/COLOR];
dynamic_txt_allowed_width = [COLOR=#000080]150[/COLOR];
[/LEFT]
[/FONT]

And automatically resize the input text area’s width accordingly. This way it makes sense to the user how much type the can fill out visually. The way I am currently doing this is hard coding the width of the input text area which works fine but I’d like to automate this.

So the real question at hand I guess is how would I figure out the aspect ratio based on font size?

I hope I have been clear

Thanks