Dice notation explained: what do 2d6, 7d12 and 3d8 + 5 mean?
A rule says '3d8 + 5'. You have a dice roller, but three separate choices to make: the number of dice, their sides and what to do with the five.
The expression is a compact instruction. Once you separate those parts, unusual dice such as d2 or d30 are no harder to understand.
Read the number before and after the d
In NdM, N is the number of dice and M is the number of sides on each. So 7d12 means seven twelve-sided dice. With ordinary additive notation, add their results. A modifier such as +5 is applied once to that total.
For 3d8 + 5, suppose the dice show 2, 6 and 7. Their total is 15, then the final result is 20. Adding five to each die instead would give 30 and would follow a different instruction.
| Expression | Dice | Possible final total |
|---|---|---|
| 1d2 | One die with 2 sides | 1–2 |
| 2d6 | Two dice with 6 sides | 2–12 |
| 7d12 | Seven dice with 12 sides | 7–84 |
| 3d8 + 5 | Three dice with 8 sides, then add 5 | 8–29 |
A total of 2d6 is not a d12
Two d6 dice cannot total 1. They also do not make every total equally likely: 7 can appear in six ordered combinations, while 2 appears only as 1 + 1. Out of 36 equally likely ordered results, that makes 7 six times as likely as 2.
One fair d12 has twelve equally likely faces. If a game asks for 2d6, replacing it with 1d12 changes both the range and the distribution. A similar-looking maximum is not enough to make two rolls interchangeable.
Other marks need the game's own explanation
Symbols for keeping dice, dropping dice or rerolling are extensions to the basic notation. Their meanings depend on the rules or software you are using. Do not assume that every roller accepts expressions such as 'keep highest'.
A percentile roll also needs a convention. D&D's basic rules use 1–100; another game may describe a zero-based table. Read the table before deciding what a pair of zeroes means. A digital d100 can give a direct 1–100 result without the physical tens-and-ones convention.
Enter the roll in Picknado
Picknado accepts up to 20 dice per roll and side counts from 2 with up to 1,000 digits. It shows individual results and their sum. It does not parse a full formula or apply game-specific modifiers; those are manual steps. For more than 20 dice, keep a running total across batches.
- For 7d12, set number of dice to 7 and sides per die to 12.
- For 3d8 + 5, roll 3 dice with 8 sides, then add 5 yourself.
- For mixed dice, such as 1d6 + 1d8, make separate rolls and add the results.
- For an unusual die, type its whole-number side count rather than looking for a preset.
Sources & further reading
The links identify sources for factual statements. Schedules and worked examples are our illustrations, not user studies.
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