Types of Dice: D4, D6, D8, D10, D12, D20 and More

From the humble six-sided cube on a board game shelf to the 20-faced icosahedron that decides whether a dungeon ranger survives the night, dice come in a surprisingly wide range of geometric forms. This page covers the major die types by face count, their mathematical properties, how they're used across tabletop games and gambling contexts, and where the distinctions between them actually matter in practice.

Definition and Scope

A die is a physical randomization device whose outcome is determined by which face lands uppermost after being thrown on a flat surface. The face count — expressed in gaming shorthand as "dN," where N is the number of faces — defines the probability distribution the die produces. A standard d6 yields any value from 1 through 6 with equal probability, roughly 16.67% per face. A d20 compresses that to 5% per face. The notation is borrowed from mathematics and popularized by the tabletop roleplaying industry, particularly through the publication of Dungeons & Dragons by Gary Gygax and Dave Arneson in 1974.

Scope matters here: this page addresses dice as physical objects, not digital simulations or probability abstractions. The full landscape of dice-driven games extends well beyond what any single die type can describe, but the dice themselves — their geometry, balance, and probability curves — are the foundation that every game sits on.

Core Mechanics or Structure

Each die type corresponds to a Platonic solid or a specific geometric approximation of one. There are exactly 5 true Platonic solids — convex, regular polyhedra where every face is identical and every vertex is surrounded by the same number of faces — and 4 of them map directly to dice in common use.

D4 — Tetrahedron
Four equilateral triangular faces. The d4 is the only standard die that cannot be read from the top face — the result is typically marked at the base edge or the vertex pointing upward, depending on manufacturer convention. It produces the narrowest uniform distribution among standard polyhedral dice, spanning 1–4.

D6 — Cube
Six square faces, the most familiar die in human history. Archaeological evidence of cubic dice dates back roughly 5,000 years, with specimens found in ancient Mesopotamia and the Indus Valley (documented in collections at the British Museum). The d6's symmetry and stackability made it the dominant die form in virtually all pre-20th-century gaming.

D8 — Octahedron
Eight equilateral triangular faces. Two square pyramids joined at the base. The d8 is used in tabletop roleplaying games (tabletop RPG dice games offer fuller context) to represent weapon damage for longswords, battleaxes, and similar arms under systems like D&D 5th Edition.

D10 — Pentagonal Trapezohedron
Ten kite-shaped faces. The d10 is not a Platonic solid but is a highly symmetric form that tumbles fairly. It appears in two configurations: a standard 1–10 die and a "percentile" variant (d%) marked 00–90, which is paired with a standard d10 to produce a d100 roll spanning 00–99 (or 1–100 by convention).

D12 — Dodecahedron
Twelve regular pentagonal faces, the fourth Platonic solid in die use. The d12 sees comparatively limited use in mainstream gaming — it appears in D&D for greataxe damage and some character class hit dice — which has given it an underdog reputation among gaming communities despite its elegant symmetry.

D20 — Icosahedron
Twenty equilateral triangular faces, the fifth Platonic solid. The d20 became culturally definitive through the D&D "d20 System," formalized in the System Reference Document released under the Open Game License by Wizards of the Coast. Its 5% resolution per face makes it sensitive to modifiers: a +1 bonus represents a meaningful 5-percentage-point shift in success probability.

D100 (Percentile)
Achieved either by pairing two d10s or by using a large 100-faced die (a zocchihedron, named after game designer Lou Zocchi, who patented the design in 1985). Percentile rolls are standard in games like Call of Cthulhu and Warhammer Fantasy Roleplay.

Causal Relationships or Drivers

Die geometry directly determines probability distribution shape. Because standard polyhedral dice produce uniform distributions — every face has equal probability — the only variable is range width. A d4 produces a flat distribution across 4 outcomes; a d20 produces the same flat shape across 20. This is meaningfully different from rolling multiple dice together. Rolling 2d6 produces a bell curve peaking at 7, because 7 can be made in 6 different combinations out of 36 possible outcomes. The choice between a single large die and a pool of smaller dice is one of the central mechanical decisions in game design, and it's covered in depth on the dice game probability page.

Manufacturing precision affects fairness. Casino-grade dice — the "perfect dice" used in craps — are manufactured to tolerances within 0.0005 inches (approximately 0.013 mm), per standards documented by dice suppliers certified by gaming commissions in Nevada and New Jersey. Consumer polyhedral dice made from injection-molded plastic carry no equivalent tolerance guarantee.

Classification Boundaries

Not all dice fit cleanly into the standard polyhedral set. Specialty and regional forms include:

The boundary between "standard" and "specialty" is largely commercial and cultural, not geometric. If a game system calls for it and a manufacturer produces it, the die is standard within that context.

Tradeoffs and Tensions

Larger face counts don't automatically mean "better" randomization — they mean wider range with the same uniform distribution. A d20 feels dramatic precisely because any result is equally plausible, including catastrophic failure and spectacular success. That volatility is a design feature in D&D, where a roll of 1 is typically a "critical failure" regardless of character skill. In games valuing consistency, designers use dice pools (multiple d6s) to produce bell curves that make average results more likely. Neither approach is superior; they serve different design goals.

Physical fairness is a genuine tension in consumer dice. A 2014 study cited by FiveThirtyEight and attributed to testing by the gaming community found that the most popular brand of d20s at the time showed statistically significant bias when subjected to saltwater float tests — a hobbyist method of checking balance by suspending a die in saturated saltwater and observing which face surfaces most often. Manufacturing flash, uneven paint fill in recessed numbers, and air bubbles in resin all contribute to bias. This is discussed further on the dice materials and construction page.

Common Misconceptions

"The d6 is the most balanced die." Not necessarily. Consumer d6s with rounded corners and pipped faces (where numbers are represented by drilled dots) can carry face-weight bias, because more pips are drilled on higher-number faces, removing slightly more material. Casino precision dice use flat faces and painted numerals specifically to avoid this.

"Rolling more dice makes results more random." More dice produce more predictable average results (closer to the expected mean), not less. Rolling 4d6 and dropping the lowest — the standard D&D 5E character generation method — produces a distribution skewed toward 12–15, which is far less random than a single d20 roll.

"A d10 can produce a true 1–100 result." Two d10s in percentile configuration produce a range of 00–99 (or 01–100 by convention), not a 1–100 uniform range without rule clarification. The "00 + 0 = 100 or 0?" question has been settled differently by different game publishers, and players should confirm the convention for their specific ruleset. The dice game rules resource addresses similar ambiguities.

Checklist or Steps

Identifying a die type from a physical specimen:

  1. Count the total number of faces on the die.
  2. Identify the face shape: triangular (d4, d8, d20), square (d6), pentagonal (d12), or kite/rhombic (d10).
  3. Note how the result is displayed — top face, bottom edge, or upward vertex.
  4. Check whether the numbering runs 1-to-N (standard) or uses alternative markings (FATE symbols, averaging numbers, percentile notation).
  5. Confirm whether opposite faces sum to N+1 (standard on d6, d8, d12, d20) — this is a quick quality check for balanced numbering layout.
  6. Cross-reference with the game system's notation to confirm the die is the correct type for the application.

Reference Table or Matrix

Die Faces Shape Platonic Solid Range Common Use
D4 4 Equilateral triangle Yes (tetrahedron) 1–4 Small weapon damage, trap damage
D6 6 Square Yes (cube) 1–6 Board games, craps, RPG damage
D8 8 Equilateral triangle Yes (octahedron) 1–8 RPG weapon damage, hit dice
D10 10 Kite (trapezohedron) No 1–10 / 00–90 Percentile rolls, RPG systems
D12 12 Regular pentagon Yes (dodecahedron) 1–12 Greataxe damage, hourly timekeeping games
D20 20 Equilateral triangle Yes (icosahedron) 1–20 Core resolution mechanic in d20 systems
D100 100 Variable (zocchihedron) No 1–100 Percentile skill checks, Call of Cthulhu
D2 2 Cylinder / lens No 1–2 Coin-flip decisions
FATE die 6 Square Yes (cube) −1, 0, +1 FATE and Fudge RPG systems

For guidance on matching dice to specific game contexts, the how to choose dice page covers selection by game type, player count, and material. The broader reference framework for dice in American recreational contexts is indexed at Dice Game Authority.

References