How far do you fall per turn?

Question

I recently began browsing the 5e PHB when I noticed that there was no distance per round when falling under the Falling category. Is there a set fall speed and if so, what is it?

Answer 1

[This answer superseded by the release of Xanathar's Guide to Everything, Nov 2017, as detailed in this answer.]

The rules have no explicit guidance on falling kinematics. Mostly.

Free-falling motion isn't tackled in the rules. Back to that in a moment.

Feather Fall allows one to fall at 60 ft. per round (6 sec.), or at a speed of 10 fps without suffering damage. Free-fall, which is injurious, should be faster than that. A little high-school physics will tell us that a body falling freely (assuming g=32 ft/s²) for 10 ft. will attain a final speed of ~25 fps. So this all makes sense: 10fps=no damage, 25fps=1d6 damage.

Distance fallen:

To me this means it's not inherently unreasonable to use the simple classical physics in this situation: assuming acceleration due to gravity similar to that experienced at sea level on Earth and ignoring air resistance at low speeds:

starting from rest: \$ d_{\text{1 round}} = 576\text{ ft} \$

starting from rest: \$ d_{n\text{ rounds}} = 576 \times n^2\text{ ft} \$

Falling speed: your average velocity during the fall would be \$\sqrt{16d}\$, in feet per second. (Your final velocity is twice that.)

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For those who really want a refresher on simple kinematics, assuming uniform acceleration and starting velocities of zero:

• \$ \text{distance traveled} = \frac{1}{2} \times \text{acceleration} \times \text{time}^2 \$
• \$ \text{final velocity} = \sqrt{2 \times \text{acceleration} \times \text{distance traveled}} \$
• \$ \text{average velocity} = \dfrac{\text{final velocity}}{2} \$
• \$ \text{time of fall} = \sqrt{\dfrac{2 \times \text{distance traveled}}{\text{acceleration due to gravity}}} \$

In non-SI units the acceleration due to gravity is approximately 32 feet per second².

Answer 2

(up to) 500 feet, by rule.

Xanathar's Guide to Everything p. 77 gives this optional rule for the rate of falling (particularly for long falls):

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.

Answer 3

The 500ft rule (c. 170m) is designed to simplify things. I also don't like the use of the word 'instantly' here. I think a more accurate representation, especially for sentient entities, would be 'before one can take an action', explaining why entities who can negate falling by taking an action, such as casting levitate or fly, cannot stop themselves in the first round of action. Why? Because they are surprised at suddenly falling and hence cannot take an action. But, it seems plausible that other entities might be able to act before one has fallen 500ft.

I'm not suggesting that new rules applying the laws of physics (in our world) or dissecting a 6-second round into sub-components are required or even desired.

Rather, I would remind everyone of the first rule of D&D: The GM is always right. The rules are meant to be guidelines, not constraints. 20d6 will kill a lot of characters, and for the sake of the story the GM may not want a character to die. On the other hand, 20d6 will not kill a lot of characters, meaning that a fall of tens of thousands of feet will not kill them, and the GM may decide that that is patently absurd and have death ensue.

The angle here is that the GM and players are telling a story, not playing a video game.