Save DC Calculator
Work out a d20-system spell save DC and attack bonus from your proficiency bonus and ability modifier, with proficiency auto-filled from level. Calculates in your browser.
Spell save DC
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Show the math
Both values start from your proficiency bonus and the relevant ability modifier:
save DC = 8 + proficiency + modifier
attack bonus = proficiency + modifier
All math runs locally in your browser.
What this does
A save DC calculator works out a d20-system spell save DC and attack bonus from your proficiency bonus and ability modifier.
How to use it
- Enter your level for proficiency.
- Enter your spellcasting modifier.
- Read the spell save DC.
- Read the spell attack bonus.
How it works
Proficiency is filled in automatically from level, and the spell attack bonus is proficiency plus your ability modifier.
save DC = 8 + proficiency + ability modifier
Understanding your result
The save DC is the number enemies must beat to resist your spell, so a higher DC means your spells land more often, and it scales with both your proficiency (from level) and your casting ability. Keeping your casting stat high is the single biggest lever, since a low DC lets even weak foes shrug off your best spells.
Example
Proficiency +3 and a +4 modifier give a save DC of 15.
Sources & methodology
Last updated .
Frequently asked questions
How is a spell save DC calculated?
It is 8 plus your proficiency bonus plus your spellcasting ability modifier.
Where does proficiency come from?
It is filled in automatically from your level, but you can override it for unusual cases.
Is my data kept?
No. Everything is computed locally in your browser.
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