I have gathered some info that will help to give you a net-to-gross
approximation. Keep in mind that most U.S. states have their own
income taxes, and a few cities do, too, and the rates vary.
Using the "Net to Gross Paycheck Calculator," and assuming a weekly
pay period, a filing status of "single", and no state or local income
taxes, a net paycheck of $850 would be generated by a gross paycheck
of $1,124.62. This uses the withholding schedules for 2006.
Net paycheck $850.00
FICA OASDI $69.73
FICA Medicare $16.31
Federal tax $188.58
Here is a screen capture of the results:
Net to Gross Paycheck Calculator
You can find links to information about your state's income tax (if
any) on this page (scroll down the page about halfway to see the list
Salary Wizard: California & other state tax rates information
This page has a Gross Pay Calculator which includes state income tax.
Just enter the data and select your state, and the calculator will do
Paycheck City: Gross Up Calculator
My Google search strategy:
Google Web Search: "net to gross" paycheck
Google Web Search: "gross-up" calculator tax
Google Web Search: "state income tax" calculator
I hope this is helpful!