1d8

1d8 is a common dice notation used in tabletop role-playing games to indicate rolling a single eight-sided die. The standard eight-sided die is an octahedron, with eight triangular faces, usually numbered from 1 to 8. When rolled, the face that lands uppermost determines the result of the roll.

The outcomes of a 1d8 roll are uniformly distributed, giving each value from 1 to 8 an equal probability of 1/8. The expected value of a single d8 is 4.5. In play, this result is often adjusted by adding or subtracting a modifier, as in 1d8+3, which shifts the range accordingly.

Common uses for 1d8 include weapon damage in many fantasy role-playing systems, damage from certain spells, or random-many outcomes within a larger system. Some games also employ multiple d8s and sum them (for example, 2d8), while others use a single d8 as part of a larger die pool or as a modifier to other rolls.

Physical and labeling details vary by manufacturer, but most d8 dice are plastic and designed as an eight-faced polyhedron. The faces are labeled with the numbers 1 through 8, and the die is rolled on a flat surface, coming to rest on one face to determine its result. In notation, 1d8 means one eight-sided die; combinations like 2d8 indicate rolling two such dice and summing the results.

See also: polyhedral dice, d4, d6, d10, d12, d20.