Attack Bonus

A character's attack bonus with a melee weapon is:

Base attack bonus + Strength modifier + size modifier

With a ranged weapon, a character's attack bonus is:

Base attack bonus + Dexterity modifier + range penalty + size modifier

Strength Modifier

Strength helps a character swing a weapon harder and faster, so a character's Strength modifier applies to melee attack rolls.

Size Modifier

Creature size categories are defined differently from the size categories for weapons and other objects. Since this size modifier applies to Defense against a melee weapon attack or a ranged weapon attack, two creatures of the same size strike each other normally, regardless of what size they actually are. Creature sizes are compatible with vehicle sizes.

Dexterity Modifier

Dexterity measures coordination and steadiness, so a character's Dexterity modifier applies when the character attacks with a ranged weapon.

Range Penalty

The range penalty for a ranged weapon depends on what weapon the character is using and how far away the target is. All ranged weapons and thrown weapons have a range increment (see Table: Ranged Weapons and Table: Melee Weapons). Any attack from a distance of less than one range increment is not penalized for range. However, each full range increment causes a cumulative -2 penalty on the attack roll. A thrown weapon has a maximum range of five range increments. Ranged weapons that fire projectiles can shoot up to ten increments.