D20 Dice Roller

Your details

How many twenty-sided dice to roll at once. Use 1 for most D&D checks; more for special spells or tests.
Advantage and Disadvantage apply only to single-die ability checks and saving throws in D&D 5e. They roll two d20s and keep the better or worse result.
A flat bonus or penalty added to the final total. In D&D this is typically your ability modifier plus proficiency bonus.
The Difficulty Class or armor class you need to meet or beat. The calculator shows the probability of hitting this number after the modifier is applied.
Toggle off and on to re-roll.
Die resultWeak Roll
5

The raw d20 face value (before modifier)

Total (with modifier)5
Probability of success30%
Expected value10.5
Critical hit chance0.05%
Critical fail chance0.05%
5
Critical fail<2Very low2-6Below average6-11Above average11-16Strong16+

You rolled 5 - failure against DC 15.

  • Rolling normally, the expected (average) die value is 10.5.
  • Your probability of meeting DC 15 is 30.0%.

Next stepIf your DM allows Inspiration, spending it grants advantage - worth about a +4 expected bonus.

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