Spell Save DC: Formula and Examples

Spell save DC is calculated as 8 + your proficiency bonus + the ability modifier used for your character’s spellcasting. Enter those two values in the calculator to get the DC a creature must meet or beat on its saving throw to avoid or reduce a spell’s effects.

Formula

Spell save DC = 8 + proficiency bonus + spellcasting ability modifier. The fixed base is 8. The proficiency bonus is added because your character is trained in using spells, and the ability modifier is the modifier for the ability that governs the spellcasting class or feature.

• Proficiency bonus (p): a bonus determined by character level in the 2014 fifth-edition rules, or by character level under the applicable 2024 rules. Enter the bonus as a signed number, such as +2.
• Spellcasting ability modifier (a): the relevant ability score modifier, such as +3. It can be negative, so enter the minus sign when appropriate.
• Spell save DC (dc): the resulting target number. A target generally succeeds on its saving throw by rolling a total equal to or greater than this DC.

The calculator’s second output, “Example save roll needed,” equals the DC. It is a simple display of the target number, not a prediction of whether a creature will succeed: the creature’s saving throw modifier and die roll also matter.

Worked Example

Using the calculator’s default inputs, proficiency bonus is +2 and the spellcasting ability modifier is +3:

1. Start with the base: 8.
2. Add proficiency: 8 + 2 = 10.
3. Add the spellcasting ability modifier: 10 + 3 = 13.

Spell save DC = 13. A creature normally needs a total of 13 or higher on the relevant saving throw to succeed. The roll may include its saving throw modifier; the target does not simply need to roll a 13 on the die.

What the DC Does

A spell save DC is the target number for saving throws called for by spells and certain other abilities. The spell’s description tells you which ability score the target uses, such as Dexterity or Wisdom, and what happens on a success or failure. A successful save does not always cancel a spell: some spells still deal reduced damage or have another partial effect.

For example, suppose a spell requires a Dexterity saving throw against DC 13. A creature with a +2 Dexterity saving throw modifier rolls a d20 and adds 2. A roll of 11 becomes 13 and meets the DC, so it succeeds. A roll of 10 becomes 12 and fails. Apply the spell’s exact wording to determine the result.

Do not confuse your spell save DC with your spell attack bonus. A spell attack is usually resolved by rolling against a target’s Armor Class, while a saving-throw spell asks the target to roll against your DC. The two calculations are related through proficiency and spellcasting ability, but they are used in different ways.

Choosing the Right Inputs

The calculator works only when you use the proficiency bonus and ability modifier that apply to the particular spell or feature. The relevant ability depends on the source of the magic and its rules. A class, subclass, species trait, feat, magic item, or multiclass feature may specify its own spellcasting ability or calculation.

• Check the feature or spellcasting rules to identify the correct ability; do not assume every spell uses the same ability.
• Use the ability modifier, not the full ability score. For example, an ability score of 16 normally gives a +3 modifier.
• Use the proficiency bonus specified by the rules for the character and feature. In the 2014 fifth-edition progression, it ranges from +2 to +6 as character level rises.
• Include any applicable bonus or adjustment only if the relevant rules say it changes the spell save DC.

For a typical single-class character using the standard formula, a level 1 character with proficiency +2 and an ability modifier of +3 has DC 13. If the ability modifier later rises to +4 while proficiency stays +2, the DC becomes 14. When proficiency increases from +2 to +3 with the ability still at +4, the DC becomes 15.

Rules Versions and Common Mistakes

The formula above is the standard spell save DC formula in the fifth-edition rules, including the 2014 rules and the 2024 revision. However, an individual feature can provide a different DC, and a game may use house rules or setting-specific text. Follow the specific rule when it overrides the general calculation.

• Using the ability score itself: add its modifier, not a score such as 16 or 18.
• Adding proficiency twice: the formula contains proficiency once. Do not add it again unless a specific feature expressly says to.
• Using the wrong ability: the character’s most important ability is not automatically the one a particular feature uses.
• Mixing up attack bonus and save DC: an attack bonus is used for spell attacks; a save DC is used when a target makes a saving throw.
• Ignoring a target’s modifier: the DC is the final target number, but the target’s saving throw total includes its own applicable modifier.

Rounding is not normally an issue with this formula: the base, proficiency bonus, and ability modifier are whole numbers in ordinary use. If a special effect changes the calculation, apply its wording rather than rounding an intermediate value by habit.

When to Recalculate and Limitations

Recalculate when your proficiency bonus changes, when the ability score that governs the feature changes, or when an applicable rule grants or removes a DC adjustment. A character may have different DCs for different features, so note which feature each number belongs to instead of assuming one displayed DC applies to everything.

This calculator gives the numerical DC from the standard formula; it does not determine which saving throw a spell requires, whether a creature is immune or resistant, or whether a particular feature uses a special calculation. Those questions depend on the spell or feature text and the rules being used at the table.

Frequently Asked Questions

What is the formula for spell save DC?
Use 8 + proficiency bonus + the spellcasting ability modifier that applies to the spell or feature.

What is a spell save DC of 13?
It is the target number for the relevant saving throw. A creature generally succeeds if its d20 roll plus its saving throw modifier totals 13 or more.

Does spell save DC include proficiency?
Yes. The standard formula adds the character’s proficiency bonus once, along with the base 8 and the relevant ability modifier.

Is spell save DC the same as spell attack bonus?
No. A spell attack bonus is added to a d20 attack roll against a target’s Armor Class. A spell save DC is the target number for a saving throw made by the target.

Which ability score determines my spell save DC?
Use the ability specified by the class, feature, or other source of the spellcasting. It is not always the same for every kind of magic a character can use.

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in p | Proficiency bonus | - | 2 | 0
in a | Spellcasting ability modifier | - | 3
out dc | Spell save DC | - | 8 + p + a | 0
out r | Example save roll needed | - | dc - 0 | 0