For me, it is around 68%, but the figure will vary widely from person to person.  I put 10% to 401k, have Federal, Soc Sec, Medicare, State taxes taken out.  Federal tax withholding will depend on the rate you select (based on number of dependents - my withholding is lower than normal since I itemize because of my mortgage interest).  Federal taxes will also depend on your tax bracket (if you make more, you will give a larger percentage).  Also, don't forget any insurance premiums that you will have taken out as well.