Hi @TheEdVerse, I have a random (and very specific!) question for you: what is the approximate ratio of spellcasters to nonspellcasters in the Forgotten Realms? 1 out of 10,000? 1 out of 100,000? Even more rare than that?

— Benjamin Huffman x Sterling Vermin Adventuring Co. (@sterlingvermin) December 29, 2020

1)
This gets asked a lot, but here we go again. ;}
The answer is always: it depends. Here’s why: literally thousands of sentient beings in the Realms have a ‘wild talent’ for some aspect of magic, due to the world being a-crawl… 2)
…with magic (wielders of the Art using it, drawing on the Weave), and everyone born into the world being exposed to flows of magic. Over time, growing numbers of sentient beings are born with the Gift (ability to wield the…#Realmslore

— Ed Greenwood (@TheEdVerse) December 30, 2020

3)
…Art). Most don’t know it, and are utterly untrained, and stay that way lifelong. Say, 1 in 9,000. A rarer few (1 in 12,000) may or may not manifest a ‘wild talent’ that lets them work magical effects without casting or… 4)
…knowing magic. An even rarer few (1 in 26,000) may spontaneously or thanks to a trigger event discover and use a natural ability to work spells by imagination, concentration, and their natural Gift; we call them “sorcerers.”#Realmslore

— Ed Greenwood (@TheEdVerse) December 30, 2020

5)
Perhaps 1 in 130,000 have the desperation or bravery to reach out to try to contact a patron and become a warlock; perhaps 1 in 300,000 succeeds.
However, of that far less rare number of beings that have the Gift (back to… 6)
…1 in 9,000 again), we have an overlap with those who want to dedicate themselves to holy service (about 1 in 4000). About half of these are accepted (1 in 8,000), and of those, about 1 in 6,000 have the ability to wield…#Realmslore

— Ed Greenwood (@TheEdVerse) December 30, 2020

7)
…divine magic (as opposed to a deity just channeling a magical effect through them, treating them like a “dumb conduit” and perhaps destroying them or burning out their minds in the process). So IF they follow temple protocols… 8)
…and don’t displease the deity, every one of those 1 in 6,000 could become clerics (as in the character class), capable of wielding divine magic. What magic they get given depends on their service, the fervency and…#Realmslore

— Ed Greenwood (@TheEdVerse) December 30, 2020

9)
…appropriateness of their prayers, and the mood/nature of their deity. Most clerics don’t get beyond 3rd level spells (the game rules concentrate on PCs, who are the standouts/mavericks/heroes, and can give us a distorted view… 10)
…of things).
However, if we go back to beings that naturally possess the Gift, and try to figure out how many become casters of arcane magic, the answer is: those very, very few who can find a tutor, and get taught, and…#Realmslore

— Ed Greenwood (@TheEdVerse) December 30, 2020

11)
…survive it.
Those who survive adventuring, or just living in the Realms once others know they can cast arcane magic, are even fewer.
So…it depends. ;}
You said “spellcasters” in your query, and that includes wizards, … 13)
…competently hurl mighty spells, or rather, unleash magic with any degree of understanding or control, are more numerous than they really are).
And the totals of, say, trained wizards will vary with time and place; if you look… 12)
…sorcerers, clerics, warlocks, and all of the variants and subclasses (druids, illusionists, etc.) which pushes the total numbers up a bit (but again, the game rules and published Realmslore tend to make us think folk who can…#Realmslore

— Ed Greenwood (@TheEdVerse) December 30, 2020

14)
…at a surviving Netherese city, like Thultanthar (“Shade”), the numbers of arcanists are much higher than if you go out into the frigid wilderness northeast of Sundabar and start looking for wizards. Outcasts in the Border…#Realmslore

— Ed Greenwood (@TheEdVerse) December 30, 2020

14)
…at a surviving Netherese city, like Thultanthar (“Shade”), the numbers of arcanists are much higher than if you go out into the frigid wilderness northeast of Sundabar and start looking for wizards. Outcasts in the Border… 15)
…Kingdoms make the numbers higher there than in, say, Tethyr. Cities are almost always far higher than in the countryside, and the countryside higher than in wilderlands, and so on.
So if we decide that the 1490s DR is our…#Realmslore

— Ed Greenwood (@TheEdVerse) December 30, 2020

16)
…time, and the Sword Coast countryside is our place, and it’s summer rather than winter (when those who can go south in search of temperatures they can survive, do so), and it’s peacetime, and no local ruler is rounding up… 17)
…wizards and imprisoning or executing them, or Zhents or Red Wizards hunting down and slaughtering non-member wizards, we might estimate (and it IS an estimate, mind) that of the 1 in 9,000 who have the Gift, perhaps…#Realmslore

— Ed Greenwood (@TheEdVerse) December 30, 2020

18)
…1 in 40,000 can cast a cantrip or two, and perhaps 1 in 70,000 have and can cast 1st level spells, and perhaps 1 in 90,000 can cast 2nd level spells. Thanks to traveling priests and the teachings of shrine and temple… 19)
…clergy, almost everyone has seen minor magic at work (but not personally experienced it), and thanks to bards and talkative traveling merchants and peddlers, nigh everyone has heard tales of spell-duels or spectacular…#Realmslore

— Ed Greenwood (@TheEdVerse) December 30, 2020

20)
…spell-hurlings or awesome feats of magic (those MageFairs, for one!), but your average “just plain commoner” in the Realms never actually sees or personally experiences magic being cast, or could hope to begin to afford to… 21)
…get trained, or to hire a spellcaster to work one spell for them.
Again, be not misled by game lore and rules, which leave the distinct impression that hundreds, if not thousands, of wizards hurl spells down any given city…#Realmslore

— Ed Greenwood (@TheEdVerse) December 30, 2020

22)
…city street in a day.
So: it depends. :}#Realmslore

— Ed Greenwood (@TheEdVerse) December 30, 2020