2d8

2d8 is a dice notation used in tabletop role-playing games to indicate rolling two eight-sided dice and summing their results. Each d8 yields an integer from 1 to 8 with equal probability, and the total therefore ranges from 2 to 16.

There are 64 equally likely outcomes when rolling two d8s (8 × 8). The counts for the possible sums are: 2:1, 3:2, 4:3, 5:4, 6:5, 7:6, 8:7, 9:8, 10:7, 11:6, 12:5, 13:4, 14:3, 15:2, 16:1. Consequently, the probability of sum s is count(s)/64. The distribution is symmetric around 9, with the peak at 9 (8/64 or 12.5%).

Statistics for two d8s: the expected value is 9, since the expected value of a single d8 is 4.5 and the sum is additive. The variance of a single d8 is (8^2 − 1)/12 = 63/12 = 5.25, so the variance of the sum is 10.5, giving a standard deviation of approximately 3.24.

Usage notes: 2d8 is commonly used for damage rolls, healing, or other numeric effects in games. In many systems, the total may be modified by adding or subtracting a bonus or penalty. Some rules may treat 2d8 as the base result with situational modifiers, critical outcomes, or situational rerolls applying separately.