Contract vs full time employee question

[marine]

Folks,

I'm sure some of you are contract based employees....
I have an opportunity to switch from a full time employee, with a full benefits package to a contract employee. (normally I wouldnt even consider this, but it is with a well known blue chip type DoD firm and involves me working from home in my underwear on the couch most of the day)

I'm trying to figure out how to translate the salary to an hourly wage while taking into account the full benefits package that I will be giving up.

I've got "carte blanche" with the number, but I don't want to go waaaay high and irk them.
Any recommendations?
So far the best I can come up with

Base Salary * 1.33 = New Total Salary (NTS) with a $ value on the benefits vice the actual benefits

then

NTS/2080 (hours worked per year) = new hourly wage
Then I'll probably tack on a few bucks to that number and give it to them.
Am I missing anything?
Any big things I need to consider before making such a switch?

 

[Agent 0659]

So you will be an ind. contractor? Or they will just pay you salary but no bennies?

What about 401K, pension, etc.?

 

[saint]

If you're an independent contractor make sure to factor that in as well. You will be footing the bill for social security and medicaid, so tack on another 7.65%