Size change -> Speed change?

[Josh the Aspie]

Hey there. You've all probably heard this a dozen times before from other people, but I am considering creating a house rule where effects that increase a person's size also increase that person's speed.

This is, at least partially, to avoid situations like the following (last few panels).

http://www.giantitp.com/comics/oots0453.html

Going from medium to large or small seems simple enough, an increase of +10 or -10 feet per round (respectively), but after that I'm sure it will need to get more complex.

Has anyone here already come up with something like this, or have advice on putting something together?

[Godskook]

It probably requires a special table to be made, cause there are Medium creatures with 20ft movement and small creatures with 30ft, and that's just off the top of *my* head(goblins and dwarves).

[Josh the Aspie]

Do you think it would be better to base it on the existing speed of the creature, and how many sizes it changes, rather than it's size, perhaps?

[Debihuman]

Not necessarily. I think that is why the Dire Creature Template [from Tome of Horrors] doesn't add any speed, but instead relies on the speed of the base animal. Some animals should become more ponderous the larger that they become. I don't think there is a standard correlation between a creature's size and its speed and that's the problem.

One of the best charts I have ever seen for this is from Expeditious Retreat Press' Book A Magical Society Beast Builder which is open game content.

Generally quadrapeds move faster than bipeds. Flying creatures tend to move faster the larger they get. However, burrowing, climbing and swimming speeds are unaffected by size. It then breaks down as to whether creatures are slow, average or fast.

I'm not that good with charts unfortunately so recreating may be a bit beyond me.

Debby

[Fitz10019]

The Plant Growth spell description mentions that larger-than-large creatures can ignore the impediments of terrain, which would be a relative and situational speed boost.