It depends on how often you are paid, and if your W-2 claims "married" or "single".
Here are the tables (I have it starting on Married and being paid every two weeks, but you can scroll up or down for other options, the math calculations are on Page 45-46):
<a rel="nofollow" target="_blank" href="
https://www.irs.gov/pub/irs-pdf/p15.pdf#page=53">https://www.irs.gov/pub/irs-pdf/p15.pdf#page=53</a>
