Dice notation
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Dice notation (also known as dice algebra, common dice notation, RPG dice notation, and several other titles) is a system to represent different combinations of dice in role-playing games using simple algebra-like notation such as 2d6+12.
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[edit] Standard notation
In most roleplaying games, die rolls required by the system are given in the form AdX. A and X are variables, separated by the letter "d", which stands for die or dice. The letter "d" is most commonly lower-case, but some notation uses upper-case "D".
- A is the number of dice to be rolled (1 if omitted).
- X is the number of faces of the dice
If the final number is omitted, it is typically assumed to be a six, but in some contexts, other defaults are used.
For example, if a game would call for a roll of d4 or 1d4 this would mean, "roll one 4-sided die."
3d6 would mean, "roll three six-sided dice." Commonly, these dice are added together, but some systems could direct the the player to choose the best die rolled.
To this basic notation, an additive modifier can be appended, yielding expressions of the form, AdX+B. The plus is sometimes replaced by a minus sign ("-") for subtraction. B is a number to be subtracted from the final total. So, 1d20+10 would indicate a roll of a single 20-sided die with 10 being added to the result. These expressions can also be chained (e.g. 2d6+1d8), though this usage is not common.
[edit] Variations and expansions
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[edit] Multipliers
In some games, the above notation is expanded to allow for a multiplier, as in AdX×C or C×dX, where:
- × denotes multiplication, and can be replaced by "/" or "÷" for division.
- C is a natural number (1 if omitted, and often a multiple of 10).
For example,
- 1d6×5 or 5×d6 means "roll one 6-sided die, and multiply the result with 5."
- 4d6×10+3 means "roll four 6-sided dice, add them together, multiply the result with 10, and then add 3."
[edit] Percentile dice (d%)
Often, the variable X in the above notation will be "100" or "%". Although a 100-sided die does exist, it is both more common and more uniformly random to use a combination of two ten-sided dice known as percentile dice, where one die represents tens and the other units; depending on the game, a roll of two zeroes can mean 100 or zero.
The d1000 is occasionally also seen, although it is more common in wargames than role-playing games.
[edit] "Keep" notation
Some games extend the standard notation to AdX(kY)+B where, in addition to the above, Y is the number of dice kept from the roll. Whether the dice omitted are the highest, lowest, or the player's choice depends on the game in question. Seventh Sea only uses 10-sided dice, and uses notation of the form 8k6, meaning "Roll eight ten-sided dice, keep the highest six, and sum them."
[edit] Low/high roll
The OpenRoleplaying.org die roller allows the use of L or H instead of the modifier B, to denote the lowest or highest roll on a single die, respectively. So 4d6−L means "Roll four six-sided dice, sum them, and subtract the lowest number rolled", or simply "Roll four six-sided dice, drop the lowest die, and add the rest." 2d+H would be "Roll two six-sided dice and sum them, then add the higher one (again)."
[edit] Fudge dice (dF)
The game system Fudge uses customised "Fudge dice", six-sided dice with two plus symbols, two minus symbols, and two blank faces, represented using "F" in place of the variable X. The plus faces count as a roll of +1; the minus faces as −1 and the blank faces as zero. Thus, 4dF+2 would be the total number of plus faces shown, minus the number of minus faces shown, plus two. "1dF" is equivalent to "1d3−2" in standard notation.
[edit] d66
Various Games Workshop systems use a d66 roll, which means rolling two six-sided dice, one representing tens and one units, analoguously to a percentile roll with two ten-sided dice. Note that there are, somewhat confusingly, 36, not 66, different possible results, ranging from 11 to 66.
[edit] d666
The game In Nomine uses what it calls the "d666" – in fact this is simply 2d6 which are used to determine whether a player succeeds in a task, with a third die to show degree of success or failure.
[edit] Stress dice
In World Tree, dice are rolled differently when determining the outcome of particularly stressful situations. World Tree represents ordinary die rolls with the usual AdX notation, but stress rolls are represented as AsX, where A and X carry the usual meanings.
[edit] O.R.E. system
The One-Roll Engine (O.R.E.) system uses only ten-sided dice and the standard notation of Ad for “roll A 10-sided dice”. But this notation is augmented with some qualifiers that modify how the result is obtained. hd (‘Hard Dice’) always have the maximum value of 10, and wd (‘Wiggle Dice’) or td (‘Thrump Dice’) can be assigned any possible value after the roll. Some games also use ed (‘Expert Dice’). These can either be rolled normally or they can be assigned (all different) values before the roll. So 3d+2ed+4td means, “choose two different values (from 1 to 10), then roll three dice, and choose another four (possibly equal) values (from 1 to 10)”. These values are not added. Instead, the number and value of equal die results is noted as matches in the form W×H where W is the ‘Width’ of the roll, the number of dice with matching values, and H is the ‘Height’ of the roll, the face up value of the matching dice.
[edit] Cyborg Commando
The Cyborg Commando role-playing game by Gary Gygax uses a dice mechanic called d10x. A roll of d10x is performed by multiplying results of two d10 dice. This gives a very non-linear distribution, with most results concentrated at the lower end of the range.
[edit] Leading Edge Games Notation
The various games by Leading Edge Games, such as Phoenix Command or Living Steel, used a different notation to indicate dice rolls: a number enclosed in parentheses, like so: (6), with the number indicating the number of sides of the die to be rolled. Otherwise the rules tended to follow standard dice notation, with the number of dice shown before the parentheses, and any modifiers after it: A(X).
