Click here to enter 2014 IRS Withholding Calculator
This calculator have five steps . First you have to enter what filing status will you use on your 2014 Income Tax Return: will it be Single, Married filing joint return, Married filing separate return, Head of Household or Qualifying widow(er).
You will also have to enter info about Child and Dependent Care Credit and Child Tax Credit. In Income and Withholding section you will have to enter he total wages, salary, and tips (excluding bonuses) you expect to receive in 2014 , total 2014 contribution to a tax-deferred retirement plan, FSA or HSA, total Federal income tax withheld to date in 2013 (including amounts withheld from bonuses or which you expect to have withheld for bonuses), Federal income tax withheld from your last salary payment etc.
There is also a video about Withholding Calculator provided by IRS.