The very last step in the IRS calculator provides information for new W-4s for both jobs -- with the assumption that you want to end the year with no refund and no balance due.
I made up some numbers and entered them into the calculator. The refund amount that it estimated I would get if I didn't change anything at all was $885. (The estimated tax liability was $54,515 and my fictional people were on track to have withholdings of $55,400.)
But, by making the changes recommended in the two W-2s below (one for each job), my fictional people would be on track to have $54,515 withheld -- resulting in an even-dollar return.
Go back to the IRS calculator, and -- on the Step 6 screen -- click on the link to Edit Your Information

Then, scroll to the bottom -- you should see a summary of what your tax withholdings would be with and without changes to your W-4s.

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-- KimberW
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