Average/optimal AC for core classes per level

Question

I've seen time and again that someone mentions someone has a low or a high AC for his class. So I'm wondering: Is there something like a list for what AC the core classes should have per level (averagewise or optimalwise)?

Answer 1

So the challenge with this question is that it's not just about classes but also about resources expended. You could be a Fighter choosing to use leather armor and two daggers or you could be a shield and heavy armor Fighter with the same stats and have a very different AC.

The other complication here is Touch AC vs. Flat-footed AC. Most characters are good at one or the other but not both.

That stated, there are really only a couple of builds that really matter here for benchmarks, so let's run some comparisons. Note that it's really less about "class" and more about "feats" + money.

The Tank: Heavy Armor + Shield

I modeled this one as a Fighter spending ~75% of their cash on defense.

• Level 3: 24 (Full Plate +1, Heavy Shield, Dex +1, Dodge +1)
• Level 5: 28 (Heavy Shield +1, Ring of Protection +1, Amulet of Natural Armor +1)
• Level 7: 31 (Full Plate +2, Heavy Shield +2, RoP +2, Dex +2)
• Level 9: 36 (Full Plate +3, Heavy Shield +3, AoNA +2, Dex +3, Dusty Rose Ioun Stone +1)
• Level 11: 40 (Dex Belt => Dex +4, Armor/Shield +4, Ring/Amulet +3)

The Light Armor Dex build

As above this Rogue is spending most of their money boosting their AC. In this case, they benefit greatly from the Dex Belt as well.

• Level 3: 20 (Mithril Chain Shirt +1, Dex +4, Dodge +1)
• Level 5: 23 (Dex +5, AoNA +1, RoP+1)
• Level 7: 25 (Chain Shirt +2, AoNA +2)
• Level 9: 28 (Chain Shirt +3, Dex +6, RoP +2)

The Wizard/Sorcerer (with some Dex)

As above, this person is spending lots of their money on basic defensive gear and using the Dex to benefit their ranged touch attacks.

• Level 3: 15 (Dex +3, Bracers of Armor +1, RoP +1)
• Level 5: 18 (Dex +3, Bracers +2, AoNA +1, Draconic Natural Armor +1)
• Level 7: 21 (Dex +4, Bracers +3, AoNA +2)
• Level 9: 25 (Dex +4, Bracers +4, RoP +2, Draconic Natural Armor +2, Dusty Rose Ioun Stone +1)

Some Takeaways

These are "max" numbers not median numbers by any stretch. In fact the numbers should reveal several things:

• Dex is really important for AC outside of Heavy Armor characters, this constitutes most of your AC.
• By level 9 the spread on AC is huge. This actually causes big problems If your fighter has AC 30 and your Sorcerer has AC 18 (typical) then you end up with creatures that can never miss the Sorcerer if they can also hit the Fighter.
• This problem only gets worse as levels go on. At some point, you stop attacking fighters and just start casting spells at them because your odds of success are better.
• Likewise creatures become impossible to "balance". Take a CR20 Red Dragon, Wyrm, it has a bite of +38. Your Sorcerer is never going to have an AC to counter that. It basically means that the Sorcerer cannot get into melee combat or it will be ripped to shreds. It doesn't matter if the Sorcerer has dropped 500k on AC items or 50k on AC items.
• Some math (Bracers +8 => 64k, AoNA +5 => 50k, RoP +5 => 50k, Belt of Dex +6 => 36k). That's 200k in AC pump for a net AC of 31. Add a Shield spell and you're still under the threshold. You'll need Morale or Luck bonuses from a Bard or Cleric bring that up to 40+ and even then, you'll probably get hit.

There are 4 defenses

• AC is not the only defense. In fact, as levels go up your Ref/Fort/Will saves become far more important. No amount of AC will save you from a Wail of the Banshee.
• Experienced players understand this problem. At some point it becomes pointless to try to max out AC and instead you throw the resources into other things. Cloak of Resistance is far more important than Ring of Protection. At some point, instead of another +1 to your armor, you buy Energy Resistance or something to give you Damage Resistance.
• There are other ways to avoid getting hit. Mirror Image, Invisibility and Fly are all important abilities that allow weaker AC creatures to survive combat.
• AC is really only one part of the puzzle. For many combats, keeping certain characters protected is just as important.

Answer 2

The vast range of options for different classes means that a "Base AC" is going to be highly variable depending on what the character has picked or is aiming to achieve.

However the pazio reference NPC Codex contains sample core classes that we can use for this data; from that we get for example:

Monk
Level  AC
1      16
5      17
10     21
15     28
20     34

However this data is specialised through each level to different subtypes, but it gives you an idea of the scope of the issue.

Answer 3

Sadly, there's no ISO benchmarks for AC on a per-class/level basis. BUT, you can get a sense on your own.

Low: a build that does NOT use many discretionary resources (gold, feats, stats) for AC purposes.

Hight: a build that uses ALL discretionary resources for AC.

E.g. A level-1 fighter using core rulebook stuff:

LOW: Scale-mail, Dex of 10, no AC feats, no shield: AC of 15

HIGH: Breast-plate, Dex of 14, Dodge feat, heavy shield: AC of 21

There's obviously more that one can do, but a 21 AC is solid for a starting tank.

Answer 4

The rule of thumb we go by is your level + 20 for ac. (This does not apply at early levels, although if you have 18 ac at level 1, that is good (At level 1 opponents average +1 or +2 to hit, they would need a ~16+ on die to hit you with 18 ac). The reasoning is because your opponents attack bonus will consist mostly of their BAB and the 20 sided die roll. Your level + 20 is saying that your opponents chance to hit is based off their weapon bonuses + relevant ability modifier * 5%. So if your opponent has 18 str, a +2 weapon, and a +1 bonus from feats they will have a 35% chance to hit you (4 str + 2 weapon + 1 feat = 7 * 5 = 35%).

The class you are playing, however, does not matter. If you break a class down by what separates them from all the other classes, the major differences are:

1) Base attack bonus
2) Fort, Refl, Will Saves
3) Hit Dice
4) Special abilities

You choose how you place your ability scores and rarely does a special ability from a class add into your AC (Monks with Wisdom would be an exception, but the wisdom would replace the armor bonus temporarily). The point is, your opponents attack bonus does not change depending on the class YOU are playing. Anyone can take a cleric, or a rogue, or a fighter, and give them the exact same armor proficiency feats, armor, and dex scores.