[C5] Calculating Combat Values (hp, AC, THAC0, dmg, blahR)

Hit Points:
[P1.18] has a good system for calculating hit points, additional notes are below:
Classes listed with a "&" in front of their Hit Die type fully add: do not figure them into Multi-classing calculation, add the hit points from that class at the end. These classes add all (even lower than previous classes) hit dice when using Dual-classing.
Mixed-classing: Takes better for both number of dice and die type; so a Paladin (d10) mixed with Ranger1 (+d8) would be +d10.
Split-classing: Calculate like Multi-classed, except do NOT divide by number of classes at the end (a lot of hit points).
Your racial hit points are added after all other calculations are made.
Armor Class:
[P1.16] has a good system for calculating Armor Class.
Remember that your race may add an AC source.
This table shows which ability scores (Str and/or Dex) are used to calculate THAC0 and damage:
Type of attack To Hit
Other Note
Melee weapon Str Str x1.5 bonus if using two-handed
Natural (fists, claws) Str+Dex+2 Str -
Grafted Melee weapon Str+Dex+2 Str Grafted is an effect generated from a spell/psionic/innate ability
Kicking Str Str -
Thrown weapon Str+Dex Str Has Missile damage limit.
Bow Dex none Can gain Str bonus with Strength Bow. Has Missile damage limit
Crossbow Dex, SR SR SR is "Strength Rating" limited to Str. Has Missile damage limit
Arquebus Dex Dex Yes, this does get Dex bonus on damage. Has Missile damage limit
Missile damage limit: A missile weapon cannot do more bonus damage than it's maximum damage it can do by itself.
An Arrow (1d6) +3/+4 fired from a Bow +5/+2 does 1d6+6 damage by itself, so it's overall max damage is 1d6+6+12 = 1d6+18.
Natural 1: A natural 1 on a to hit roll indicates an automatic miss. There are no "fumbles".
Natural 20: A natural 20 on a to hit roll indicates an automatic hit. There are no "critical hits".
Optional Rule #1: A natural 20 does double damage if a (non-automatic) 20 would have hit the target.
Optional Rule #2: A natural 20 allows another bonus attack this segment versus that same target.
blahR (MR, PR, RR, etc.):
See [C9] for the effects of blahR. blahR's are lowered by 5% per caster level above 12.
If you have multiple sources of the same blahR, use the following calculation:
Net Resistance = (highest source) + (2nd highest)/2 + (3rd highest)/3 + ...
Thus, if you have 60% MR, 40% MR, 30% MR, and 20% MR, your total MR would be 60 + 40/2 + 30/3 + 20/4 = 95%.