what do you consider a "good" AC?

[dabrutsqad]

I've got a 4Ftr/3Wiz/5Spellblade and with buffs at one point was able to get up to 40, but that was +5 Dex bonus, w/ Expertise, Shield Spell, RoP +2, Celestial Armor, Fighting defensively, Etc.
We've got a group of 7 11 & 12th level characters and mine was the only one to get his high. Normally, this would be good except when dealing with a single enemy powerful enought to meet our CR. When a creature with multi-attack, BAB +25 & SR 26 starts whacking your melee fighters you realized just how nice it was to have a swarm of kobolds and a Barbarian with Great Cleave/Whirwind Attack.
I've been using the 5th/10th/15th Progs for the Iconic Characters in Enemies and Allies to give me an idea of what our party members should do. Not much else in the book, but if a friend or your GM has a copy take a look. I think our party's being gipped of loot.

 

[Spatzimaus]

Don't just say "eh, they'll hit me anyway, I won't worry about AC", for three reasons:

1> Power Attack
2> Expertise
3> Touch/Ray spells

If I can increase my AC by 7, that's 7 less points the fighter can Power Attack for if he still wants to hit me. If someone wants to disintegrate me, adding a bit more AC that works against touch attacks goes a LONG way keeping me alive.

I'd say a "Good" AC is one where an equal-level fighter hits you 50% of the time. That'd be 11+level+(their STR bonus). An "Average" AC would be about 5 lower, for Power Attacking guys or those Rogues/Monks with the lower BAB.

So, at level 14, that gives around 30 as a "Good" AC or 25 as an "Average" AC. That matches the ACs of the reference NPCs in the DMG pretty well, at least for the fighter-types.

 

[hong]

I'd say a "Good" AC is one where an equal-level fighter hits you 50% of the time. That'd be 11+level+(their STR bonus).

Try 11 + level + Str + 1 (Weapon Focus) + level/4 (weapon enhancement bonus) + 2 (for miscellaneous buffs).

 

[Numion]

AC 40 isn't that hard at higher levels. Cleric in full plate and appropriate spells can reach that easily. At level 15+, IIRC, an AC of 30+ is pretty reasonable, getting closer to 40 as the levels rise.

 

[Gunslinger]

My 30th level monk's AC is 91. But he can't even hit himself on anything other than 20s. Of course that's with an uber amount of money to spend. What your AC should be really depends on your role in the party. If you're the party's tank, then by level 4 you AC should be around 23. By about tenth level it should be around 30.

 

[CRGreathouse]

13 + 1.3 per level is a good approximation.

 

[Endur]

Good AC: enemy needs to roll "20"s

A good AC means that the enemy needs to roll a 20 to hit you.

This does two things, it massively cuts down on damage that your character takes, and it also makes criticals very rare (since only a 20 is a threat and only a 20 can confirm). At low levels, criticals can kill characters, so this is important.

A good AC for level 1 is 18. For instance, a 1st level character with chainmail, large shield, and dex 12.

A good AC for level 5 is 22. For instance, a 1st level character with full plate, large shield, dex 12, and some sort of magic +1 to ac.

My 9th level character (Paladin6/Fighter1/Dwarven Defender 2) has a base AC of 26.
+1 mithril full plate (9)
+1 large shield (3)
+1 ring of protection (1)
dex 14 (2)
dwarven defender ac bonus (1)

Under some circumstances, that AC can be much higher:
dodge feat (1)
defensive stance (4)
against giants (4)
so the AC could rise to 35

plus possible spells from a friendly caster:
magic vestment on armor (+3 additional)
magic vestment on shield (+3 additional)
barkskin (+4 natural ac)
cat's grace (+1 ac)
haste (+4 ac)

so final ac could be as high as 50, but most of the time its somewhere in the 30's

If I was going to give a formula for a good ac, I would say 20 + level of the character. i.e. ac 30 for 10th level characters, ac 40 for 20th level characters, etc.

Tom

 

[Archer]

A "good" AC is your level +20. That gives you good protection against most enemies you will face at your CR.

Wizard with mage armor + shield = 21 AC

Fighter with breastplate + shield + 3 dex = 21 AC

As you go up level you get that amulet of natural armor +1, ring of protection +1, full plate +1, shield +1 and so on then you start getting +2's.

My cleric has AC 30, 34 w/ haste at 10th level. I have no natural armor bonus which I am trying to fix.

 

[Stalker0]

A good AC is when the gorillion was charging into me, instead of dropping my die from my hand shaking so hard, I was found sipping a cappucino and talking with a very lovely lady, almost completely unaware of the situation at hand

 

[Celebrim]

As a general rule, I think AC should be at least character level + 15. Some classes will have slightly lower (rouges, wizards without spells running). Some slightly higher (fighters, clerics). But a 14th level fighter should have at least an AC approaching 30 with means of improving it if necessary (expertice for instance). Otherwise, the first high level opponent with power attack and/or rend will put him out of combat very early. And if not 30 or higher then he should have some other valuable defensive measure to show for it - like energy immunity.

Increasing AC is generally cheaper than increasing damage output. Invest in it. Players AC advantage over monsters is tradiationally thier ace in the hole in D&D.

My 7th level cleric has an AC of 25.