Dice roll analysis
Advantage and disadvantage
Granting an advantage or a disadvantage on a 1d20 roll has following effects on its expected outcome:| Roll | Mean | Median | Mode |
| Basic | 10.5 | 10.5 | n/a* |
| w/ advantage | 13.825 | 6 | 20 |
| w/ disadvantage | 7.175 | 15 | 1 |
| Net effect | ±3.325 | ±4.5 | — |
As evident from different magnitudes of the mechanic's net effect on the mean and the median, its influence is nonlinear and cannot therefore be reduced to a flat modifier of ±3, ±4, or ±5.
Death saving throws
Because the probability of a successful death save is slightly above 1/2 (55%, to be precise) and because rolling a natural 20 at any point (even after two failed saves) causes an unstable character to immediately regain 1 HP, the death save mechanic in 5E is actually surprisingly lenient, with following expected outcomes:| Outcome | Probability | Percent |
| Conscious at 1 HP | 1451/8000 | ~18.1% |
| Stable at 0 HP | 3310/8000 | ~41.4% |
| Dead | 3239/8000 | ~40.5% |
In other words, when you drop to 0 HP (and barring additional damage or healing), you only have an about 2 in 5 chance to actually die, and a 1 in 5 chance to get right back up.
