Roll a d8: eight-sided dice roller

Rolling the d8 on this page

The dice above are already set up as d8s. The Dice selector goes from 1 to 6, and the modifier is changed with + and −. That number is applied once to the total: with 2d8+3 the two dice are added together and then the 3.

To roll, press Roll or drag the dice with your mouse or finger and drop them in the tray; they tumble with real physics and stop on their own. When they settle, the page shows the top face of each die and the total. If you play D&D, a longsword (1d8 + Strength modifier) or a 2024 Cure Wounds (2d8 + modifier) comes out in a single gesture.

The octahedron: shape, numbering and fairness

The eight-sided die is a regular octahedron, one of the five Platonic solids. It looks like two square-based pyramids glued base to base. It has 8 equilateral triangle faces, 12 edges and 6 corners, with four faces meeting at each corner.

Unlike the d4, the octahedron has faces in parallel pairs, so one face always ends up on top and you read it like an ordinary die. On standard dice opposite faces add up to 9: 1 sits opposite 8, 2 opposite 7, 3 opposite 6 and 4 opposite 5. It follows the same logic as the six-sided die, whose opposite faces add up to 7: if a small manufacturing flaw favoured one side, the high and low number of each pair would balance out on average.

Is it fair? Yes, for the same reason as every Platonic solid: any face can be moved into the position of any other by a symmetry of the solid, so none has a geometric advantage. In practice it rolls far better than a d4, because its edges are less sharp (neighbouring faces meet at about 109.5°, against about 70.5° on the tetrahedron).

The d8 in D&D 5th edition

The d8 is one of the dice that turns up most often in D&D, because it appears in three places at once: hit points, weapons and spells.

Hit die

Under the 2014 rules, six of the twelve classes use a d8 hit die: bard, cleric, druid, monk, rogue and warlock. At 1st level they start with 8 hit points plus their Constitution modifier, and at each later level they add 1d8, or a fixed 5 if they would rather not roll, plus Constitution. Hit dice are also spent during short rests to recover hit points.

1d8 weapons

Greatclub, light crossbow, battleaxe, flail, longsword, morningstar, rapier, war pick, warhammer and longbow. The quarterstaff and spear go from 1d6 to 1d8 when wielded in two hands (the versatile property). In the 2024 revision the trident becomes 1d8 as standard.

Spells and features

• Cure Wounds: 1d8 + modifier in 2014; 2d8 + modifier in 2024.
• Sacred Flame and Ray of Frost: 1d8 damage at low character levels.
• Chromatic Orb: 3d8.
• Bardic Inspiration: the bard’s die starts as a d6, becomes a d8 at 5th level, a d10 at 10th and a d12 at 15th.

Other uses for an eight-sided die

In Savage Worlds, where every skill is measured by a die type from d4 to d12, the d8 sits in the middle of the scale. Against the usual target number of 4, a d8 succeeds 5 times in 8 (62.5%).

A d8 is handy away from role-playing as well:

d8 probabilities (calculated tables)

Each face has a 1 in 8 chance, 12.5%. The average of a d8 is 4.5.

That settles a common question when levelling up: rolling 1d8 for hit points gives 5 or more exactly half the time, and its average (4.5) is half a point below the fixed value of 5. Taking the fixed value gains a little on average and gives up the chance of a 6, 7 or 8.

With two d8s (Cure Wounds under the 2024 rules, for instance) there are 64 combinations and 9 is the most likely total:

And if you roll several d8s at once, this is what to expect:

Where the gaming d8 comes from

Nineteenth-century wargames and those of the mid-twentieth century ran on six-sided dice alone. Polyhedral dice reached the table in the early 1970s: in 1972 Creative Publications, a Californian company selling maths teaching aids, offered sets of five dice shaped as the five Platonic solids (d4, d6, d8, d12 and d20). Don Lowry, publisher of the Tractics wargame rules, resold them to his customers, and in 1973 Gary Gygax wrote an article in Lowry’s mailer on how to combine the probabilities of these dice.

When D&D appeared in 1974 it adopted them, although in the first edition the d8, like the d4 and d12, came up only rarely. Over the years the d8 gained ground until it became one of the most repeated damage and hit point dice of 5th edition.

In antiquity, Plato had linked the octahedron with air in the Timaeus, as part of his theory of the four elements.

Tips for rolling the d8