Does a dex penalty apply to armor class [3.5]

[Teapot Salty]

Hey guys. One of my characters will be having negative dex (roleplaying element) and I was wondering if that applies to ac. I don't see how trying to dodge attacks makes you easier to hit (unless your jumping into them :smalltongue:) Thanks, and as always, go nuts.

[Sartharina]

Yes, it applies to AC, because you don't even have average ability to dodge.

Failure to even attempt to dodge is -5 AC.

[Teapot Salty]

Yes, it applies to AC, because you don't even have average ability to dodge.

Failure to even attempt to dodge is -5 AC.

So I will have a higher ac when flat footed?

[Flickerdart]

So I will have a higher ac when flat footed?
No. You only lose a Dexterity bonus, not a penalty.

[nedz]

Armor Class

Your Armor Class (AC) represents how hard it is for opponents to land a solid, damaging blow on you. It’s the attack roll result that an opponent needs to achieve to hit you. Your AC is equal to the following:

10 + armor bonus + shield bonus + Dexterity modifier + size modifier

Note that armor limits your Dexterity bonus, so if you’re wearing armor, you might not be able to apply your whole Dexterity bonus to your AC.

Sometimes you can’t use your Dexterity bonus (if you have one). If you can’t react to a blow, you can’t use your Dexterity bonus to AC. (If you don’t have a Dexterity bonus, nothing happens.)

The last sentence is relevant.

[HighWater]

If you need help visualising why a negative dex value still makes you easier to hit when flatfooted, use the following fluff-explanation:

Even people unaware of their enemies tend to be at least somewhat in motion (especially in DnD encounters). People with a low dexterity move less, and when they move, they move in a more rigid, predictable fashion (which is why you're easier to hit than average in normal combat ánd when you're not aware you're in combat). Flatfooted is not the same as being motionless.
Basically, being more movable than average does you no good when you're not actively avoiding something that tries to hit you (you're in motion, but the motion doesn't necessarely improve or decrease your changes of being hit because it's unrelated to being hit), while being less movable than average still harms you when you're not acively avoiding something that tries to hit you (you're still sluggish and predictable).

People unable to move (paralysed, asleep, unconscious, bound or in other ways helpless or rendered motionless) lose all their dexterity and are treated as if having Dex 0, which gives a -5 on AC.

This leads to the conclusion that a guard who is ordered not to move a muscle while on guardduty (very common in royal guards, think buckingham palace) should probably be treated as having Dex0 or Dex 2 when snuck up on, provided he failed his listenchecks by a wide enough margin. "Bound" by his orders, really.