Closest Calld20 advantage and disadvantage
Roll two twenty-sided dice and keep the higher, or the lower. Here is what that does to your odds.
Chance of hitting each target
With advantage you roll two twenty-sided dice and keep the higher. With disadvantage you keep the lower. The table shows the chance of the die you keep showing at least the number you need.
| You need | Normal roll | With advantage | With disadvantage |
|---|---|---|---|
| 2 or higher | 95.0% | 99.8% | 90.3% |
| 3 or higher | 90.0% | 99.0% | 81.0% |
| 4 or higher | 85.0% | 97.8% | 72.2% |
| 5 or higher | 80.0% | 96.0% | 64.0% |
| 6 or higher | 75.0% | 93.8% | 56.3% |
| 7 or higher | 70.0% | 91.0% | 49.0% |
| 8 or higher | 65.0% | 87.8% | 42.3% |
| 9 or higher | 60.0% | 84.0% | 36.0% |
| 10 or higher | 55.0% | 79.8% | 30.3% |
| 11 or higher | 50.0% | 75.0% | 25.0% |
| 12 or higher | 45.0% | 69.8% | 20.3% |
| 13 or higher | 40.0% | 64.0% | 16.0% |
| 14 or higher | 35.0% | 57.7% | 12.2% |
| 15 or higher | 30.0% | 51.0% | 9.0% |
| 16 or higher | 25.0% | 43.8% | 6.3% |
| 17 or higher | 20.0% | 36.0% | 4.0% |
| 18 or higher | 15.0% | 27.8% | 2.3% |
| 19 or higher | 10.0% | 19.0% | 1.0% |
| 20 or higher | 5.0% | 9.8% | 0.3% |
What the chart tells you
- The average roll is 10.5 normally, 13.82 with advantage and 7.18 with disadvantage.
- Advantage helps most in the middle. When you need an 11, it lifts your chance from 50% to 75%, which is worth the same as a +5 bonus. When you need a 20, it only lifts 5% to 9.75%.
- A natural 20 comes up 5% of the time normally, 9.75% with advantage and 0.25% with disadvantage.
- A natural 1 is the mirror image: 5% normally, 0.25% with advantage and 9.75% with disadvantage.
- Rolling the same number on both dice happens 5% of the time.
How to work it out
To fail with advantage, both dice have to miss. If a single die misses with probability m, both miss with probability m times m, so the chance of success is 1 minus that. With disadvantage both dice have to succeed, so you multiply the single-die chance of success by itself.
More dice odds
- Dice odds library: every chart in one place
- Two dice (2d6) odds chart
- Three dice (3d6) odds chart
- 4d6 drop the lowest: ability score odds
- Five of a kind and other five-dice odds
- Attacker against defender dice odds
- Two twenty-sided dice (2d20) odds chart
- At least one six in 1 to 10 rolls
- Dice calculator: the exact odds for any total with any number of dice, plus a dice roller.
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Every figure on this page was computed by counting all possible outcomes. Game names mentioned here are trademarks of their owners; this site is not affiliated with or endorsed by them.