I have heard it said that 5e does not balance its encounters with respect to magic items; in other words it does not consider possession of magic items when defining appropriately challenging encounters. But what about mundane items? Specifically, plate mail. Due to its cost, it stands out dramatically from other, mundane items.
I have read numerous forum posts discussing the "correct" rarity of such an item, and what character levels are fitting for PCs acquiring it. What troubles me about this is plate is a significant part of the Heavy Armor proficiency – if plate (and to a lesser extent, splint) is not available (either by gold restrictions or the DM saying it's hard to find) then Heavy Armor proficiency becomes much less valuable to a PC. Light Armor users easily get to 16 AC, and Medium Armor users can get to 17 at half of the cost of plate. Now, plate is 18 AC, but it comes at a great financial cost, Strength restrictions, and Stealth disadvantage. Seemingly, the only real benefit is that they can also get to 17 AC cheaper/more easily than any other armor proficiency.
Still, in many campaigns plate is out of reach for the first five (or more) levels, making the Heavy Armor proficiency relatively weak for any classes that offer it. Even once that point is reached, AC tends to be less important than raw HP or magic resistance/saves at later levels – so by the time plate becomes available, it matters less than it would have earlier.
In short, I identify that the availability of plate mail as a huge "swing factor" in the value of Heavy Armor proficiency.
Do any 5e official sources (source books, designer statements, or Adventurer's League) offer any indication on the appropriate time to allow PCs to have plate?
Best Answer
RAW: Somewhere between levels 5 and 11
Six levels is a lot of variance, so let's see what we can discern. Looking over the expected results from the treasure tables in chapter 7 of the dmg and the "starting gear" table for adventures not starting at level one, a character (or party, depending on loot-sharing) should be able to obtain plate mail by around level 7; A level 5 party may be able to afford this by pooling their resources.
The tables are all somewhat imprecise, but we know that at level 5, you start with about 600GP and at level 11, you start with about 5600GP. Note that ~600GP is consistent with expected loot from CR-appropriate monsters during levels 1-4.
IF we assume that the scaling is actually linear and not tiered (meaning that a smooth-ish line can be drawn from each level's expected loot, rather than a 5th level character having 500 more gp than a 4th level character) and we use the two points mentioned above (level 5 with 600 gp and level 11 with 5600 gp), then we can find a distribution. (though, if such a graph were to exist, it would probably not be linear, but I digress)
5000GP over 6 levels is ~850 gp per level.
That gives us:
level 5 with 600GP
level 6 with 1450GP (just shy of full plate)
level 7 with 2300GP
level 8 with 3150GP
level 9 with 4000GP
level 10 with 4850GP
level 11 with 5700GP (close enough)
from which we can derive.....
Around level 7 for an individual
Around level 5 for a party