Know your odds
Dice probability
Exact odds for any roll, worked out rather than simulated. Ask the same question twice and you will get the same answer, because nothing here is rolling dice behind the scenes.
Dice Probability Calculator
Enter any dice notation and see every possible result with its exact odds.
Dice Sum Probability
How likely each total is when you add dice together, and why 7 dominates on 2d6.
Target Number Odds
The chance of hitting the number you need, on any dice and any modifier.
Compare Dice
Put two dice expressions side by side and see which actually wins more often.
Average Dice Roll
The average result of every die, and how to work one out for any roll.
Quick answers
- What is the average roll of a d20?
- 10.5Every face is equally likely, so the average sits exactly halfway between 1 and 20.
- What are the odds of a natural 20?
- 5%One face in twenty. With advantage it rises to 9.75%.
- What is the most likely roll on 2d6?
- 7Seven comes up on 6 of the 36 combinations, or 16.67%.
- What are the odds of beating 15 on a d20?
- 30%Six faces out of twenty clear a target of 15, counting 15 itself.