d20 dice roller
The icosahedron that decides every attack, save and skill check. Pick normal, advantage or disadvantage, add your bonus, roll.
Roll history
Your results appear here and stay on this device only.
How much is advantage worth?
People say advantage is "about +5". That is only true in the middle. Move the target and watch the gap change.
You need a natural 6 or higher on the d20.
Here advantage adds 18.8 percentage points, the same as a flat +3.8. It peaks at +4.75 when you need an 11, and shrinks towards +1 when you need a 2 or a 20. Chance with advantage is 1 − (miss chance)²; with disadvantage it is (hit chance)².
Assumes attack-roll rules: a natural 1 always misses and a natural 20 always hits.
d20 odds at a glance
| Need at least | Normal | Advantage | Disadvantage |
|---|---|---|---|
| 5 | 80% | 96.00% | 64.00% |
| 8 | 65% | 87.75% | 42.25% |
| 10 | 55% | 79.75% | 30.25% |
| 11 | 50% | 75.00% | 25.00% |
| 12 | 45% | 69.75% | 20.25% |
| 15 | 30% | 51.00% | 9.00% |
| 18 | 15% | 27.75% | 2.25% |
| 20 | 5% | 9.75% | 0.25% |
The average natural roll is 10.5 normally, about 13.82 with advantage and 7.18 with disadvantage. Want the odds for any other roll? Type it into the dice probability calculator.
Questions people ask
How do I roll a d20 with advantage?
Choose Advantage and press Roll. Two d20s are rolled and the higher one counts; in notation that is 2d20kh1. Disadvantage keeps the lower one (2d20kl1).
What are the odds of a natural 20?
5% (1 in 20) on a normal roll. With advantage it rises to 9.75%, with disadvantage it falls to 0.25%.
Do advantage and disadvantage stack?
Not in D&D 5e. Any number of sources of advantage still means two dice, and if you have both advantage and disadvantage they cancel and you roll one d20.
What is Elven Accuracy?
A 5e feat that lets you roll three d20s and keep the highest when you have advantage on certain attacks. Choose "Triple (Elven Accuracy)" here, which rolls 3d20kh1.
Is a natural 20 always a success?
On attack rolls, yes, and it is a critical hit. On ability checks and saving throws in 5e (2014 rules), a natural 20 is not an automatic success; many tables house-rule it anyway.