When something refers to an ability bonus instead of an ability modifier does that mean that you only add the modifier if the ability score is positive, or are “bonus” and “modifier” to be read as interchangeable?

Normally when you attack if you have a negative strength modifier you apply the negative strength modifier to damage. The flat-footed condition on the other hand specifically refers to a dexterity bonus instead of a dexterity modifier. I was wondering whether, if you had a negative dexterity modifier, your AC would get better when you're flat footed.

  • 7
    \$\begingroup\$ RAW make it pretty clear as @Nyoze's answer describes, but for flavor it's kind of funny to imagine that being flat-footed does improve your AC if you have cruddy Dex. Like normally you're so clumsy that your attempts to dodge make things worse for you, but if you're caught unawares you stand a better chance. \$\endgroup\$
    – tobek
    Jul 20, 2015 at 15:30

1 Answer 1



A Flat-Footed penalty will still apply.

According to Ability Scores:

A positive modifier is called a bonus, and a negative modifier is called a penalty.

With this in mind, when looking for an ability bonus, only use a positive modifier.


Looking at Flat-Footed AC with a Dex of 9

According to Armor Class

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, your AC does not change.

This specifically mentions bonus, not modifier. Since a Dex of 9 is a -1 modifier, or a -1 penalty, you would still apply this penalty to your armor class when surprised.

Based on this, we can use the following calculations to demonstrate:

Standard Combat:

Dex 12 = +1 Bonus   - 11AC
Dex 9  = -1 Penalty -  9AC

While Surprised

Dex 12 (Bonus Removed) - 10AC
Dex 9  (No Bonus)      -  9AC
  • \$\begingroup\$ I'm confused: Your first segment argues that a penalty does not apply when a "bonus" is explicitly called out. Your second quotation asserts no bonus = no AC change. From this you determine that a "penalty" causes an AC change. In fact, from your second quote, one derives "If you only have a Dexterity penalty, your AC does not change." \$\endgroup\$ Jul 20, 2015 at 18:14
  • \$\begingroup\$ @EricTowers The flat-footed penalty includes losing your Dexterity bonus to AC (if any), and losing your attacks of opportunity (unless otherwise negated by a feat). The second part states just that having a negative modifier to AC from dexterity means your AC won't get any worse. This rule helps saves characters with lower dexterity (they're already clumsy enough!). They still lose their attacks of opportunity for the turn. \$\endgroup\$
    – phyrfox
    Jul 20, 2015 at 18:37
  • \$\begingroup\$ I'm a little confused about what you guys are getting at... But I'll try and clear it up. 9 Dex means you have a Dex Bonus of +0, so that +0 doesn't get applied when surprised, and you'll still have your -1 penalty. \$\endgroup\$
    – Nyoze
    Jul 21, 2015 at 1:36

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