How thick is modern MBT armor (DR 2000)?

[Balor Patch]

Originally Posted by Fred Brackin

For a simpler example, the armor belts on an Iowa-class Battleship average 20" thick and probably are made out of RHA.

That's 12.1", although the turret faces are 18" plus change. While quality varied, belt armor throughout the dreadnought era was always face-hardened. The WW2 British plate was particularly good.