D&D Spell Save DC Calculator

What Is a Spell Save DC?

When you cast a spell that forces enemies to make a saving throw, they must roll a d20 and add their saving throw bonus. If their total equals or beats your Spell Save DC, they succeed (and usually take half damage or avoid the effect).

Formula

Spell Save DC (Difficulty Class) = 8 + Proficiency Bonus + Spellcasting Ability Modifier + Item Bonus

Your proficiency bonus always applies here. There is no “proficient in your own spell save DC” question to answer, and the DC is a fixed number rather than something you roll.

Two useful things follow from the formula. Your spell save DC is always exactly 8 higher than your spell attack bonus, because both are proficiency plus your casting modifier. And it goes up at exactly the four levels your proficiency bonus does, at 5, 9, 13 and 17, plus whenever you raise the casting ability itself.

Spellcasting Ability by Class

Both of the Fighter and Rogue spellcasting subclasses run on Intelligence, because both borrow the wizard spell list. That trips people up, since neither class has any other reason to care about the stat.

Proficiency Bonus by Level

Practical Example

A level 11 Wizard with an Intelligence modifier of +5 and no magic items: Spell Save DC = 8 + 4 + 5 = DC 17. Enemies need 17 or more on a d20 plus their saving throw bonus to resist.

A creature with a +2 save fails that 70% of the time. One with a +6 save, which is what a monster’s good save looks like at this tier, fails 50%. That gap is the whole reason spells target the save a monster is bad at rather than the one the spell description happens to name first.

Saving throws have no natural 20

An attack roll auto-hits on a 20 and auto-misses on a 1. A saving throw in the 2014 rules does neither. If the arithmetic says a creature cannot reach your DC, it cannot reach it, full stop, and a 20 on the die changes nothing. That is why this page shows 0% and 100% where the attack bonus calculator stops at 5% and 95%.

Item Bonuses

The items that raise a spell save DC are class-flavored and mostly uncommon to very rare, not legendary: Rod of the Pact Keeper for warlocks, Arcane Grimoire for wizards, Moon Sickle for druids and rangers, Rhythm-Maker’s Drum for bards, All-Purpose Tool for artificers. Each comes in +1, +2 and +3 versions.

Watch out for the near misses. A Staff of Power gives +2 to armor class, saving throws and spell attack rolls, and it does not raise your spell save DC. Neither does a Wand of the War Mage, which is spell attack rolls only. Read the item text for the words “spell save DC” before adding anything here.