02. THAC0 to Armor Class

[Ironnerd]

THAC0 to BEz Armor Class
I actually like THAC0, but to most modern players it does not make a bit of sense. 5th Edition’s mechanic of roll ≥ the target’s Armor Class on 1d20 is much cleaner and simpler. To be quite honest, it’s a better mechanic anyway.

To get from THAC0 to Armor Class, just do a bit of math. Subtract the BECM Armor Class (BAC) from 9 (the BAC of an un-armored character), and add 10.

► AC = 19-BAC (but it’s easier with a couple of tables).

ARMOR ......... LEGACY ..... BEz
None ............ 9 ........ 10
Leather ......... 7 ........ 12
Scale ........... 6 ........ 13
Chain Mail ...... 5 ........ 14
Banded Mail ..... 4 ........ 15
Plate Mail ...... 3 ........ 16
Shield ......... -1 ........ +1

The table below allows for conversion of a wide variety of Armor classes, and is useful for Monsters and characters with +x armor.

LEGACY AC ..... 9 .... 8 .... 7 .... 6 .... 5 .... 4 .... 3 .... 2 .... 1 .... 0 .... -1 ... -2 ... -3 ... -4 ... -5 ... etc...
BEz AC ........ 10 ... 11 ... 12 ... 13 ... 14 ... 15 ... 16 ... 17 ... 18 ... 19 ... 20 ... 21 ... 22 ... 23 ... 24 ... etc...



Before an attack can be made, however, the character's To-Hit Adjustment will have to be determined (see next post)