Size modifier

From NWNWiki

The size modifier is based on the size of the creature in question, with the exception that modifiers for disarm attempts are based on the size of the weapon in question.

For attack bonus and armor class, the following table is used. This modifier stacks with all other modifiers and does not count towards any caps. (This modifier is not shown on the character sheet.)

Size	Size Modifier
Colossal	-8
Gargantuan	-4
Huge	-2
Large	-1
Medium	+0
Small	+1
Tiny	+2
Diminutive	+4
Fine	+8

For grapple checks (e.g. Evard's black tentacles and Bigby's grasping hand) and knockdown/disarm attempts, the following table is used:

Size	Size Modifier
Huge	+8
Large	+4
Medium	+0
Small	-4
Tiny	-8