Quote Originally Posted by olskool View Post
WHY? Monks get both their DEX modifier and their WIS modifier added to their AC. The average Monk is going to start with an AC of 15 or more. Fighters in my game will be lucky to have Ringmail or Scalemail Armor (I use all of the AD&D 1e armors) by 3rd Level. That is only an AC of 14. At 6th level, they may have moved up to Butted Chainmail (AC15) or Rivetted [Chain]Mail (AC16) and the majority won't see Brigandine/Splintmail (AC17) or a Coat of Plates or Platemail (AC18) until 10th Level due to the cost of armor. Full Plate at AC19 (200 Gold Sovereigns or 20,000 Silver Guilders, or 2,000,000 Copper Pennies in cost) doesn't show up until well after 10th Level. The 1st Level Monk stands a better chance of survival in a fight than a 5th or 6th Level Fighter based on AC alone.
Fighters, in their starting kit, get Chainmail (for heavy) and a shield. That's 16 AC (Chainmail) plus 2 (Shield) plus potentially another 1 (Defensive Fighting Style) if they REALLY want defense.

Monks, meanwhile, start with an AC cap of 16 (16 Dex and Wis) in point buy or Standard Array, and only hit the Fighter's initial AC at level 1 (Chainmail, no shield, no style), 8 (Chainmail and Shield), or 12 (all three). And that means they've invested less in Constitution.

Meanwhile, the Fighter will most likely have Full Plate by tier 2, going by the normal treasure hauls in the DMG.

Now, you're free to run your game otherwise-but if you're going by the books, the Fighter's AC massively trumps the Monk's, if they care about it.