How would you determine the exact federal withholding for a paycheck based on number of dependents in the United States? Is there a formula or a specific percentage of your gross based of number of dependents?
The number of withholdings you have is based on your W-4, of which your number of dependents is a factor, but not the only one. Whether you're married, whether your spouse works, your income levels, etc all factor in.
Note that there is an IRS calculator that you can use to get exact numbers.