Here is what you're looking for...
Bottom right side of the page under calculators.
Don't re-gear to match what came from the factory with 3.27's, lol.
I don't know which engine you have, but for the most part I would go with 4.10's with 31's if you re-gear.
Here is another good calculator I used before I re-geared. It was very accurate, you need to find out what the gear ratio in 5th is.
2006 F150 FX4 Super Crew - Bilstien 5100s leveled 2", 35" KM2s, 4.56 gears, Detroit locker, Eaton E-Locker, Traction Bars, AEM intake, Xcal 2
2010 VW Golf TDI 6MT