Players use spell slots as a meta concept to manage a character. For instance, Liz the Wizard gets so many spell slots at this level, and so many spell slots at that level. It says so right there in the book.

But does Liz the Wizard know about spell slots? After all, she is not aware of the Player's Handbook. Spell slots are meta, right?

So, are casters aware of spell slots?

(Related question: What is a spell slot in-lore, and how does it justify the limits on casting spells?)

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    \$\begingroup\$ @3C273, have you ever noticed when you ask a question it asks if you want to answer it? The "what is a spell slot in-lore" question got me thinking, and I decided this question and answer might be helpful. \$\endgroup\$
    – Jack
    Commented Sep 15, 2018 at 11:57
  • \$\begingroup\$ Related: How does D&D Vancian magic make sense in-game? \$\endgroup\$
    – mxyzplk
    Commented Sep 16, 2018 at 13:06

3 Answers 3


Yes, Casters know about spell slots.

TL;DR: Casters have all the information necessary in-game to figure out that spell slots are a real thing, something which can they can investigate and count, and something that affects their day-to-day lives as spellcasters.

Here's how.

In Liz's case, "after years of apprenticeship and countless hours of study" she has learned to cast spells!

She knows three cantrips which she can cast at will. She has a spellbook which contains six spells. She can spend time each morning memorizing some of her spells. However many she can memorize, it's the same, one day to the next.

She can cast one or more of those memorized spells two times in a day.

(Her players writes a 1 in the box next to level.)

Life is good!

Time passes. Liz has some adventures, gains some experience.

One day, perhaps after additional study, she finds she can memorize one more spell and not only that, she can cast three spells a day! And, she's been able to add to the spells in her book. The magic is strong with this one!

(And, of course, her player crosses out the 1 next to Level and writes 2. Yay!)

Again time passes. Liz has some adventures, gains some experience.

Again one day, she can memorize one more spell and not only that, she can cast a whooping six spells in a day! Plus she's been able to add more spells to her book. Truly she is a force to be reckoned with!

(And, of course, her player crosses out the 2 next to Level and writes 3. Whoopee!)

Now Liz notices something interesting. She can cast magic missile six times in a day. Or she can cast magic missile four times and darkness twice. Or, and this blows her mind, she can cast magic missile twice but she can add some oomph to it and get four missiles. But when she does that, each time she does a four-missile magic missile, she gets once less cast of darkness that day.

Now, Liz is pretty smart. She certainly has the smarts to figure this out. And she's motivated. After all, how many magic missiles in a day can be literally a life-and-death question. But maybe she isn't all that detail-oriented, and she doesn't put it all together. But it is all there. Spell slots are real things to her which are discoverable and countable.

Maybe she doesn't call them slots. Maybe she calls them points, or pips, or meters, or quizzles. But it's entirely reasonable that she says, "Hey, Rogue, I only got two quizzles left! I can cast some darkness, and that uses them both, or I can hit 'em once with a magic missile and still have a quizzle left. What do you want to do?!"


Of course, no table has to play this way. You could assume that somehow how many spells Liz can cast in a day is not invariant, and that The Wizard Table is just an average or an abstraction.

But if at your table it makes sense for Liz to know she's got slots, you can go ahead and let her know that, without fear of meta or OOC.


Liz thinks to herself, hmmm, obviously some spells are more powerful than others, some take one quizzle, some take two. It's almost like I could group spells together into . . . levels. No, tiers is better. Spell tiers. Interesting. Wow, if I could only learn a spell of the third tier. Perhaps some day I'll reach another level, hmm no that's not a good word, plateau is better, yes plateau of power. Yes, maybe some day I will reach another plateau of power and learn a new tier of spells. There's that fireball thing I've been working on . . . .

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    \$\begingroup\$ That last reminded me of how we rationalize spell levels from years ago in game. The nine levels are broken into 3 circles each with 3 tiers... so a level 5 spell was 2nd tier; 2nd circle... Pretty sure we got that out of a Dragon or some such or a variation anyway. \$\endgroup\$
    – Slagmoth
    Commented Sep 15, 2018 at 2:48
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    \$\begingroup\$ Whoever edited me, thank you! It's embarrassing to misspell missile. However, I reverted a couple of your edits out of sheer pedantry. In Liz's speech and thoughts she's referring to an effect (some darkness) and not specifically a spell named darkness. \$\endgroup\$
    – Jack
    Commented Sep 15, 2018 at 11:17
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    \$\begingroup\$ Would casters ever use the expression "spell slot"? \$\endgroup\$ Commented Sep 16, 2018 at 22:50
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    \$\begingroup\$ @PinkSweetener Pink, who knows? I see nothing about the concept that actually means anything that actually has anything to do with the meaning of the word slot. "Slot" could be replaced with any word representing a unit. I made up a word "quizzle" in my fanciful example. \$\endgroup\$
    – Jack
    Commented Sep 17, 2018 at 0:52
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    \$\begingroup\$ @PinkSweetener: The characters are speaking Common (or some other language), not English, so they will not use the exact phrase "spell slot." But this is no different from any other in-character conversation. Whatever word they use can only be reasonably translated as "spell slot." \$\endgroup\$
    – Kevin
    Commented Feb 11 at 2:07

Allow me to throw a general rule philosophy your way that you may already have heard about : The Murky Mirror (courtesy of The Angry GM. Strong language warning). While it doesn't directly answer your question, it implicitly states that if it's in the rule, there is SOMETHING that casters are aware off.

A word of warning : the AngryGM's article presents the Murky Mirror as the way he runs his game in general. This is the way he eliminates (or maybe he incorporates) metagaming and out-of-character/in-character dissonance in his game. I think this is way too extreme for me to run in my games, but I think the basic premise has merit to interpret game mechanics and manage some OOC information questions.

The core of the Murky mirror is worded by the GM in this way :

The players and the characters are reflections of each other in a murky mirror. They aren’t perfect reflections. But they are synchronous. If the players are sitting around and talking, then so are the characters. They are saying basically the same things, though they might be using different words or abbreviating or whatever. Hell, I know the characters aren’t even speaking English. But if a player is communicating, so is their character.

So, for example, when the player is saying “my character refuses to help because he thinks the orcs are all savages because he saw them murder his parents,” his character is probably saying something like “scum like you butchered my parents and I’d rather have every one of my fingers broken then lift one of them to help a monster like you.”

So, if your table accepts the Murky Mirror interpretation, no matter the universe and the fiction's rules, spell slots are a known and measurable thing in the fiction's universe. It's up to the player to make up his mind to use that information or not.

In your example, Liz the wizard probably doesn't think "I have 2 1st-level spell slots", but she knows "[she] can reliably cast 2 spells before night". Whether she pictures spell slots as magical contraption held in her mind, mental stamina, links to the source of magic, an actual rule of the universe that she can only cast two spells... that is up to the player or GM to decide (or the source book). But spells slots exist in some form in the fiction. Because there's in the rule and you're talking about them. At least according to the murky mirror interpretation.


The goal of this answers is to answer your question from a specific point of view : the Murky Mirror interpretation of the game. This view was originally, from reading the AngryGM's article, meant to address the problem of metagaming as a whole and break the Mythical Line Between Player and Character. The article also advocates this as the way every moment of the game is run or interpreted, which I don't agree with as I've explained in the first paragraph. While I've found it a helpful tool for some situations, I don't feel the need to apply this principle as a solid rule in my games.

Like in your own answer, every table is free to accept it or not. But I have found that this view of things help make sense a number of situations and questions like this one.

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    \$\begingroup\$ I don't see the logical in having a character say something bad about Orcs, just because the player says something bad about Orcs. I have an internal monologue in real life. I am capable of thinking one thing about a situation and acting and verbalising completely different there is no reason why a player and a character have to do the same things. \$\endgroup\$
    – Sarriesfan
    Commented Sep 15, 2018 at 6:59
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    \$\begingroup\$ I think you misunderstood. The example is meant to demonstrate that what the character says doesn't have to be exactly what the player said, so e.g. "I'm out of spell slots" might become "My strength is expended" in the fiction. I don't think it means "every out of character comment becomes an in character action." \$\endgroup\$ Commented Sep 15, 2018 at 8:39
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    \$\begingroup\$ While Ol' Angry's Murky Mirror is a very useful tool, it's tangential to the question. My question (and answer) is that spell slots are an actual in-game thing, perhaps esoteric and arcane, but nevertheless as real as weight or a sword. Still, you get an upvote for just bringing it in to the conversation. \$\endgroup\$
    – Jack
    Commented Sep 15, 2018 at 11:55
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    \$\begingroup\$ I think we're in essential agreement, although I guess we're disagreeing on detail. For instance, you say, "In your example, Liz the wizard probably doesn't think 'I have 2 1st-level spell slots'", and the actual point of the question is asking if spell slots are actually things that a caster would be aware of. I guess you're saying by the Murky Mirror, it doesn't matter. \$\endgroup\$
    – Jack
    Commented Sep 15, 2018 at 14:52
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    \$\begingroup\$ You're right. I think we can agree to disagree. But if lizz thinks "I have two more astral-links to 2nd circle manifestation", is this different to you from "spell slots"? Maybe it is actually. But to me it's the same. \$\endgroup\$
    – 3C273
    Commented Sep 15, 2018 at 14:55

Yes, they'd have to be.

According to the rules, a 1st level wizard has two 1st-level spell slots, and can only cast two per day. Narratively, that means they know they can only cast two spells. Any time they attempt to cast a third, it fails, so they're certain to be aware of this limitation, whether or not the mages of their guild use the term "spell slot".

The Arcane Recovery class feature specifically lets a wizard recover expended spell slots. They must certainly be aware of the concept of spell slots if they have the specific ability to recover spell slots.

There's lore precedent for spellcasters being aware of the game-rule limitations of spells. In the Forgotten Realms during the third edition era, where the range of fireball increased with the caster's level, wizards were described as judging their relative skill by holding contests to see who could shoot a fireball the furthest.


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