DMG p. 282 gives guidance for modifying NPC stat blocks to adapt them for specific monster races. For lizardfolk, one of the listed modifications is a "+3 natural armor bonus to AC".

A friend and I are arguing over whether or not the Lizardfolk NPC template in the DMG get a bonus to AC while wearing armor, or whether it's only a natural AC bonus.

Does the Lizardfolk bonus to AC apply when you are wearing armor as well, or only when you have no armor?


It is pretty strongly implied (PHB p 14) that it would not apply to a monk's nor barbarian's unarmored AC abilities - they provide a full calculation in lieu of worn armor.

DMG Page 276 specifies how natural armor bonus works.

A monster that doesn't wear armor might have natural armor, in which case it has an AC equal to 10 + its Dexterity modifier + its natural armor bonus.

The PHB specifies that you don't combine different methods (excepting shields, fighting styles, and magical bonuses); you use which ever is better. Let's take a dex 14 lizardman monk with Wis 14. and Studded plus shield He can go:

  • Natural Armor: 10 + 2 (dex) + 3 (natural armor) = 15
  • Monk: 10 + 2 (dex) + 2 (wis) = 14
  • Studded: 12 (SL) +2 (dex) +2 (shield.) = 16

One can argue (and I'd allow, based upon other examples in the MM),

  • Natural Armor plus shield: 10 + 2 (dex) + 3 (Natural) + 2 (shield) = 17

Note: the PHB quote:

Some spells and elass features give you a different way to calculate your AC. If you have multiple features that give you different ways to calculate your AC,you choose which one to use.

  • 2
    \$\begingroup\$ But this isn't "a different way to calculate", this is just a bonus. \$\endgroup\$ – Adeptus Oct 21 '15 at 4:06

I see this as having two possible outcomes.

The first is that the bonus is only applied to the lizardfolk when they're not wearing armour. On page 276 of the DMG it says this:

If your monster wears manufactured armour, its Armour Class is based on the type of armour worn (see the Player's Handbook for armour types). A monster that doesn't wear armour might have natural armour, in which case it has an AC equal to 10 + its Dexterity modifier + its natural armour bonus.

Nowhere does it say that a creature gets to add their natural armour bonus on top of whatever "manufactured" armour they might be wearing.

The feature also specifically says that it's a natural armour bonus. Which, to me, can be read as a bonus that's only applied the lizardfolk's natural armour, not any other armour.

The second, and this seem like a far more reasonable interpretation; it was pointed out in the comments that it's a +3 bonus to AC and the type of bonus is "natural armour bonus". Because this is a bonus to AC and not a new way of calculating AC it would stack with armour.

So basically, scales tend to be harder than the fleshy meat of other creatures and lizardfolk still have scales protecting them even if they're wearing armour. Thus they gain an extra bonus for that natural protection on top of what the armour gives them.

  • \$\begingroup\$ From other usage of armour bonuses (in this and earlier editions), I think it's safe to say "natural armour bonus" means an armour bonus of type "natural", not a bonus that only applies to natural armour. \$\endgroup\$ – Adeptus Nov 24 '15 at 1:34

It applies even when armored, as it's a bonus, not a different way to calculate AC

While page 276 implies that Natural Armour is in lieu of AC gained from manufactured armour, Natural Armour grants you a numeric bonus to AC, not a new way to calculate it. Relevant quote:

A monster that doesn't wear armour might have natural armour, in which case it has an AC equal to 10 + its Dexterity Modifier + its natural armour bonus

While this does strongly imply that Natural Armour is a new calculation, I would like to refer you to the Monster Manual, specifically the section on players being cursed with lycanthropy. If we look at the werewolf specifically, it says this (emphasis mine):

The character gains a strength of 15 if his or her score isn't already higher, and a +1 bonus to AC while in wolf or hybrid form (from natural armour)...

Neither the section on Natural Armour nor the section on player lycanthropes say that you do not gain this bonus when wearing armour. The Natural Armour section implies it, but it does say that Natural Armour is a Natural Armour Bonus, implying that it would stack.

Seeing as nothing explicitly forbids the use of armour with your natural armour bonus, and Natural Armour is described as a Natural Armour Bonus with a value typically in the range of +1 to +3, we can add our Natural Armour Bonus to our Armour Class.

You could argue that Natural Armour changes your unarmoured AC calculation, but examples from the Player's Handbook all specifically say that they alter your unarmoured AC calculation if they don't grant a bonus. This again implies that Natural Armour stacks with manufactured armour.


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