Your speed is determined by your race and your armor. Your speed while unarmored is your base land speed.
Difficult terrain, obstacles, or poor visibility can hamper movement. The hampered condition also reduces you move speed by 5 for each level. If it would reduce your speed to 0 you become Paralyzed.
If you are carrying more weight then your character could do so easily your movement speed is reduced.
Movement in Combat
By spending 1 action you may move your move speed. If you spend the entire round running in a straight line, you can move quadruple your speed. If you do something that requires a full round you can only take a 5-foot step.
Bonuses to Speed
Many spells and magic items can affect a character’s speed. Always apply any modifiers to a character’s speed before taking into account armor and encumbrance. Multiple bonuses of the same type to a character’s speed don’t stack.
When measuring distance, everything is calculated in 5 ft increments, if using a battle map with hexes/squares each hex/square is equal to 5 ft. If the direction goes diagonal for squares the first hex is worth 5 ft (1 square) of movement and the second diagonal is worth 10 (2 squares), the third is worth 5, and the 4th is worth 10 etc.
When determining the closest creature, measure in feet. If there is a tie determine the closest creature randomly.
Moving through a Friendly Square
You can move through a square occupied by a friendly character, unless you are charging. When you move through a square occupied by a friendly character, that character doesn’t provide you with cover.
You can’t move through a square occupied by an opponent, unless the opponent is helpless. You can move through a square occupied by a helpless opponent without penalty, though some characters may be large enough to impede your movement simply by being there. In such cases it may require 5 or more extra feet of movement to traverse through the square.
Ending Your Movement
You can’t end your movement in the same square as another creature unless it is helpless.
Moving through an Opponents square
A trained character can attempt to move through a square occupied by an opponent see the Acrobatics skill.
Very Small creatures
Creatures with a size index of less than ¾ do not count as occupying a square for purposes of movement. They provoke when moving even just 5 ft and cannot take the 5 ft step action.
Square Occupied by Creatures with a very Large or very Small size index.
Any creature can move through a square occupied by a creature whose size index is 4x more than their own.
A big creature can move through a square occupied by a creature whose size index is ¼ their own.
Some creatures break the above rules, check the creatures stat block for more information.
Terrain and Obstacles
Difficult terrain hampers movement. Each 5 ft of movement in difficult terrain costs double, and you cannot take the run, charge, or 5 ft step actions while moving into or across difficult terrain.
Like difficult terrain, obstacles can hamper movement. If an obstacle hampers movement but doesn’t completely block you must spend double the amount of movement to move past the obstacle. If you cannot finish the movement you must stop. Some obstacles may also require a skill check to bypass. Others still can block movement entirely and do not allow characters to move through them.
You can squeeze through or into a space that is at least half as wide as your normal space. Each move into or through a narrow space uses double the normal move speed required, and while squeezed in a narrow space you take a -4 penalty on attack rolls and is denied their dexterity bonus to Defense. A creature can squeeze past an opponent while moving but it can’t end its movement in an occupied square.
To squeeze through or into a space less than half your space’s width, you must use the Athletics skill. You can’t attack while using Athletics to squeeze through or into a narrow space, you take a -4 penalty to Defense, and you lose any Dexterity bonus to defense.
Special Movement Rules
Accidentally Ending Movement in an Illegal Space
Sometimes a character ends its movement in a position that is not allowed. Move the character back to the closest legal space for that character to have ended their movement.
Double Movement Cost
When your movement is hampered in some way your movement costs double
Large and Small creatures in combat
Small, Tiny, and Diminutive Creatures
Creatures with a size index less than ¾ and more than 1 have special rules relating to position, reach, and weapon size. Very small creatures take up less than 5 ft of space. This means that more than one such creature can fit into a single square denoted by their size index. To determine the number of creatures that can fit in a 5 ft square divide 1 by the size index. Tiny creatures (size index ¼) can fit 4 in a square, while diminutive (size index 1/16) can fit 16. Creatures with a size index less than ¾ typically have a natural reach of 0 feet, meaning they can’t reach into adjacent squares. They must enter an opponent’s square to attack in melee. This provokes an attack of opportunity from the opponent. Since they have no natural reach, they do not threaten the squares around them. You can move past them without provoking attacks of opportunity. They also can’t flank an enemy.
Large, Huge, Gargantuan, and Colossal Creatures
Creatures that take up more than 5 ft of space typically have a natural reach of 10 feet or more, meaning that they can reach targets even if they aren’t in adjacent squares. Unlike when using a reach weapon, a creature with natural reach of more than 5, still threatens against creatures who are adjacent to it.