how to calculate width of micro-strip line ?

please help me out how to calculate the width of microstrip line ?

im using CST microstudio but now im calculating all the parameters manually. so this is the only parameter left to calculate. please help me how to calculate the width of microstrip line.

refer
http://www.referencedesigner.com/tutorials/si/si_06.php
http://mcalc.sourceforge.net/
http://www.eeweb.com/toolbox/microstrip-impedance

and u will get lot of calc like this in website..google it..

It's very easy actually. In CST menu tab choose Macros --> Calculate --> Calculate analytical line impedance, a new window will open so now choose "Thin microstrip line". Type in your dimensions and press calculate, keep changing your width "W" until you reach around 50ohm for Zo.