[h=5]Increasing Hit Dice[/h] As a creature gains Hit Dice, many of its game statistics change.
Size: Adding Hit Dice to a creature can also increase its size. An increase in size affects a creature’s Defense, attack rolls, and grapple checks, as shown on Table: Creature Sizes, as well as physical ability scores and damage, as shown in the descriptions of the creature types.
Defense: An increase in size affects a creature’s Defense, as shown on Table: Creature Sizes. An increase in size might also improve a creature’s natural armor bonus to Defense, as shown on Table: Adjustments to Physical Abilities and Natural Armor. Note that a natural armor bonus stacks with an equipment bonus from armor.
Attack Bonus: Table: Creature Saves and Base Attack Bonuses shows how a creature’s base attack bonus improves as it gains Hit Dice. A change in the creature’s size also modifies its attack rolls, as shown on Table: Creature Sizes. Both values must be counted when recalculating a creature’s attack bonus.
Grapple Modifier: An increase in size affects a creature’s grapple modifier, as shown on Table: Creature Sizes.
Damage: An increase in size also increases the amount of damage a creature deals with its natural weapons.
Saving Throws: Table: Creature Saves and Base Attack Bonuses shows how a creature’s saving throw bonuses improve as it gains Hit Dice.
Ability Scores: An increase in size affects a creature’s Strength, Dexterity, and Constitution, as shown on Table: Adjustments to Physical Abilities and Natural Armor.
Skills and Feats: As shown on Table: Bonus Skill Points and Feats by Creature Type, a creature may gain additional skill points and feats depending on its type.
Table: Adjustments to Physical Abilities and Natural Armor
| Old Size 1 | New Size | Str | Dex | Con | Natural Armor Improvement |
| Fine | Diminutive | - | -2 | - | - |
| Diminutive | Tiny | +2 | -2 | - | - |
| Tiny | Small | +4 | -2 | - | - |
| Small | Medium-size | +4 | -2 | +2 | - |
| Medium-size | Large | +8 | -2 | +4 | +2 |
| Large | Huge | +8 | -2 | +4 | +3 |
| Huge | Gargantuan | +8 | - | +4 | +4 |
| Gargantuan | Colossal | +8 | - | +4 | +5 |
| 1 Repeat the adjustment if the creature moves up more than one size category. |
| Type | Bonus Skill Points | Bonus Feats |
| Aberration | +2 per extra HD | +1 per 4 extra HD |
| Animal | - | - |
| Construct | - | - |
| Dragon | 6 + Int modifier per extra HD | +1 per 4 extra HD |
| Elemental | +2 per extra HD | +1 per 4 extra HD |
| Fey | +2 per extra HD | +1 per 4 extra HD |
| Giant | +2 per extra HD | +1 per 4 extra HD |
| Humanoid | +1 per extra HD | +1 per 4 extra HD |
| Magical beast | +1 per extra HD1 | +1 per 4 extra HD |
| Monstrous humanoid | +2 per extra HD | +1 per 4 extra HD |
| Ooze | - | - |
| Outsider | 8 + Int modifier per extra HD | +1 per extra HD |
| Plant | - | - |
| Undead | +2 per extra HD | +1 per 4 extra HD |
| Vermin | - | - |
| 1 Magical beasts with an Intelligence of 1 or 2 gain no bonus skills as they advance. |
Size: Adding character classes to a creature never affects its size.
Skills: Creatures that take levels of a character class do not gain as many skill points as a human character of the same class. Creatures get 4 fewer skill points at 1st level than a human character and 1 fewer skill point each level thereafter; see Table: Skill Points per Class Level for Nonhumans.
Feats: Creatures with 1 or fewer Hit Dice that acquire character class levels advance as human characters do, but they gain only one bonus feat at 1st level instead of two.
Talents and Abilities: Creatures that advance by character class gain special talents and abilities, which are noted here.
Table: Skill Points per Class Level for Nonhumans
| Basic Class | Skill Points per Level1 |
| Strong | 2 + Int modifier |
| Fast | 4 + Int modifier |
| Tough | 2 + Int modifier |
| Smart | 8 + Int modifier |
| Dedicated | 4 + Int modifier |
| Charsimatic | 6 + Int modifier |
| Advanced Class | Skill Points per Level |
| Soldier | 4 + Int modifier |
| Martial Artist | 2 + Int modifier |
| Gunslinger | 4 + Int modifier |
| Infiltrator | 6 + Int modifier |
| Daredevil | 4 + Int modifier |
| Bodyguard | 2 + Int modifier |
| Field Scientist | 6 + Int modifier |
| Techie | 6 + Int modifier |
| Field Medic | 4 + Int modifier |
| Investigator | 4 + Int modifier |
| Personality | 4 + Int modifier |
| Negotiator | 4 + Int modifier |
| Campaign-Specific Advanced Class | Skill Points per Level |
| Mage | 6 + Int modifier |
| Acolyte | 4+ Int modifier |
| Shadow Slayer | 2+ Int modifier |
| Occultist | 4+ Int modifier |
| Telepath | 4+ Int modifier |
| Battle Mind | 2+ Int modifier |
| 1 Humanoids with 1 or fewer Hit Dice advance as human characters do. At 1st level, multiply the number of skill points per level by 4. |
