[RPG] the difference between 1/3, 1/2, and full casters


I saw in a recent answer a reference to 1/3 casters and 1/2 casters, and have never encountered this terminology before:

Paladin's are known as 1/2 casters, so their spell progression isn't as big as full casters.

What does it mean to be a 1/3 caster vs a 1/2 caster vs a full caster? How does one distinguish between the three, and which classes correspond to which types of caster?

Best Answer

"1/X Caster" is shorthand for how quickly a character gains "spellcaster levels" (and with them, more spell slots)

The progression for each of these spellcaster types looks like this, with the first column representing Character Level as a Single-classed X and the other columns representing the "Spellcaster Level" they have as that Single-classed X at a given level.

Character Level Full Half Third
1 1 - -
2 2 1 -
3 3 2 1
4 4 2 2
5 5 3 2
6 6 3 2
7 7 4 3
8 8 4 3
9 9 5 3
10 10 5 4
11 11 6 4
12 12 6 4
13 13 7 5
14 14 7 5
15 15 8 5
16 16 8 6
17 17 9 6
18 18 9 6
19 19 10 7
20 20 10 7

The classes that fall into these categories are:

Full Half Third Other
Bard Artificer* Arcane Trickster Warlock†
Cleric Paladin Artificer (Unearthed Arcana)
Druid Ranger Eldritch Knight

*The Artificer is a Half-Spellcaster, but unlike other Half Spellcasters, they gain their spellcasting feature at level 1, instead of level 2, and are treated like level 1 spellcasters at that level.
†Warlocks are unique in that their spell access resembles that of a Full Spellcaster, but their Spell Slots are completely divorced from the system that all other spellcasters use, so they need their own category.

Your spellcaster level determines how many spell slots you have, and the maximum level of spell slot that you'll have will (usually) be half your spellcasting level, rounded up.

So if you're a level 9 Paladin (Half Spellcaster), you have a Spellcaster level of 5 (See the Character Level 9 row for a Half Spellcaster). Therefore, you have spell slots equivalent to a level 5 Cleric (Full Spellcaster) and to a level 13 (or 14 or 15) Eldritch Knight (Third Spellcaster)—and for each of these characters, their Spell Slot total is:

  • 4 1st Level Slots,
  • 3 2nd Level Slots,
  • 2 3rd Level Slots.

"1/X Caster" also comes into play in the Multiclassing Rules

What kind of Spellcaster you are affects how your levels are added together when you Multiclass into multiple kinds of spellcaster.

Spell Slots. You determine your available spell slots by adding together all your levels in the bard, cleric, druid, sorcerer, and wizard classes, half your levels (rounded down) in the paladin and ranger classes, and a third of your fighter or rogue levels (rounded down) if you have the Eldritch Knight or the Arcane Trickster feature.† Use this total to determine your spell slots by consulting the Multiclass Spellcaster table.

Multiclassing, Player's Handbook, pg. 164

†Artificers have a special rule: when adding their levels for multiclassing purposes, you round up after dividing by two, instead of rounding down. Note also that Warlocks are not included in this list; again, their Spellcasting is completely different from other classes, so they aren't considered in calculating a character's normal spellcasting level.

For example, suppose we have a Multiclassed Wizard 5/Eldritch Knight 11. We add their levels by first dividing them by the level of spellcaster they are, so we take 5 Wizard Levels (5 * 1/1 = 5) and 11 Eldritch Knight Levels (11 * 1/3 = 3.666 → Rounded Down to 3) and add them together to find that this character is the equivalent of a Level 8 Spellcaster, gaining 4 1st Level Slots, 3 2nd Level Slots, 3 3rd Level Slots, and 2 4th Level Slots.