Does deliberately falling cost movement?

Question

If you willingly fall on your turn does it cost movement?

As a DM I'm thinking about how to handle things such as creatures who are immune to being prone, diving into the water from a height, or a flying creature diving off a cliff and taking a fall before taking flight. There are many circumstances where you can fall without taking damage or being knocked prone afterward, and I'm not sure how to determine movement following the dive.

For example, my character walks up to a ledge above a 10 foot drop to the ground below. After taking 5 feet of movement to step off the ledge, I allow myself to fall. When I hit the ground have I used 15 feet of movement or just 5?

Answer 1

Here are the rules on falling (PHB, p. 183):

A fall from a great height is one of the most common hazards facing an adventurer. At the end of a fall, a creature takes 1d6 bludgeoning damage for every 10 feet it fell, to a maximum of 20d6. The creature lands prone, unless it avoids taking damage from the fall.

The fall itself wouldn't cost movement (from the pool of movement available to you on your turn). The rules on falling don't say "you move" or reference your pool of movement in any way; your ability to fall (intentionally or otherwise) isn't limited by how far you can normally move in a turn. (Informally, it might be called a kind of "forced movement", since you're being forced to move by the effects of gravity.)

This interpretation is confirmed in the rules on opportunity attacks:

You also don't provoke an opportunity attack [...] when someone or something moves you without using your movement, action, or reaction. For example, you don't provoke an opportunity attack [...] if gravity causes you to fall past an enemy.

However, if you take damage and thus land prone, it will cost movement equal to half your speed to get up afterwards:

Combatants often find themselves lying on the ground, either because they are knocked down or because they throw themselves down. In the game, they are prone. You can drop prone without using any of your speed. Standing up takes more effort; doing so costs an amount of movement equal to half your speed. For example, if your speed is 30 feet, you must spend 15 feet of movement to stand up. You can't stand up if you don't have enough movement left or if your speed is 0.

To move while prone, you must crawl or use magic such as teleportation. Every foot of movement while crawling costs 1 extra foot. Crawling 1 foot in difficult terrain, therefore, costs 3 feet of movement.

Assuming you have a speed of 30 feet, if you spend 5 feet of movement to step off a ledge, you will take 1d6 bludgeoning damage and land prone. Then it will cost another 15 feet of movement (half your speed) to stand up and continue moving; alternately, you could remain prone and continue moving, but you'd only be able to move 12.5 feet. (Your DM may have you round down to 10 feet if you're playing on a grid map.)

However, if you are for some reason able to land without falling prone or taking damage, then you could move 5 feet and fall off the ledge, land on the ground below, then continue moving as normal.

Answer 2

Falling does not cost movement.

PHB 190 details the actions that do cost movement:

Your movement can include jumping, climbing, and swimming.

Falling is not part of those actions.

Also, having falling cost movement doesn't make sense--what if you have a speed of 30ft, walk 25ft, and drop another 10ft? If falling cost movement, then you'd run out in the middle of the fall and be stuck 5ft off the ground.

Answer 3

Falling won't cost movement, but you will take damage from it, as specified in p. 183 from PHB, and you will fall prone

A fall from a great height is one of the most common hazards facing an adventurer. At the end of a fall, a creature takes 1d6 bludgeoning damage for every 10 feet it fell, to a maximum of 20d6. The creature lands prone, unless it avoids taking damage from the fall.

So, even if you only spent 5ft on your case, you will have to spend more 15ft (half the usual speed - 30) to stand up before you can keep moving (or you can move crawling).

Answer 4

Xanatar's Guide to Everything confirms that falling does not cost any movement.

The rules for falling are

A fall from a great height is one of the most common hazards facing an adventurer. At the end of a fall, a creature takes 1d6 bludgeoning damage for every 10 feet it fell, to a maximum of 20d6. The creature lands prone, unless it avoids taking damage from the fall.

and they do not state that you spend your movement (or part of it) for the falling: V2blast's answer covers this aspect in great detail.

Moreover, this is confirmed also by the XGtE:

The rule for falling assumes that a creature immediately drops the entire distance when it falls.

Since a creature immediately drops the entire distance, this implies that no movement is used to cover this distance, even if it is greater than a character's speed.

Be aware that the above quote, even if it is included into an optional rule, refers to Basic Rules for falling.

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XGtE provides also some optional rules for falling from great heights and for flying creatures. The second optional rule (Flying Creatures and Falling) could be of some use if the character has a flying speed.

Rate of Falling

When you fall from a great height, you instantly descend up to 500 feet. If you’re still falling on your next turn, you descend up to 500 feet at the end of that turn. This process continues until the fall ends, either because you hit the ground or the fall is otherwise halted.

The above snippet confirms that one does not have to spend their movement while falling, otherwise one cannot fall for 500 feet.

Flying Creatures and Falling

If you’d like a flying creature to have a better chance of surviving a fall than a non-flying creature does, use this rule: subtract the creature’s current flying speed from the distance it fell before calculating falling damage. This rule is helpful to a flier that is knocked prone but is still conscious and has a current flying speed that is greater than 0 feet. The rule is designed to simulate the creature flapping its wings furiously or taking similar measures to slow the velocity of its fall.

In this case, it is specified that the movement can be spent for slowing the falling, for diminishing the damage.

The second part of this optional rule says:

If you use the rule for rate of falling in the previous section, a flying creature descends 500 feet on the turn when it falls, just as other creatures do. But if that creature starts any of its later turns still falling and is prone, it can halt the fall on its turn by spending half its flying speed to counter the prone condition (as if it were standing up in midair).

This hence allows to use half of the flying speed for stopping the fall. A strict reading suggests that you can use this strategy in two successive rounds in which one is falling from a height greater that 500 feet, but a DM may allow to use half of the movement to stop the falling also for smaller heights.