Random Tables and Dice: Turning Rolls into Results

Random tables use a dice roll or another randomizing method to select one result from a defined list of entries or ranges. The die creates an input; the table determines how that input maps to a result. A clear record therefore needs both the dice procedure and the table boundaries.

Ranges and boundaries

A table may assign 1–10 to one result, 11–20 to another, and so on. Every possible roll should have a defined destination unless the rules intentionally include a reroll, no result, or special outcome. Check whether the table uses 00–99, 01–100, or another convention before interpreting a percentile roll.

Equal and weighted tables

Equal-sized ranges give each entry the same probability under an equal-probability roll. Unequal ranges create a weighted table: an entry assigned 1–5 is more likely than one assigned only 6. A table can therefore change the distribution even when the die itself is unchanged.

When a table includes repeated entries, explain whether repetition is intentional weighting or a duplicate label. The source should be preserved so editors can distinguish a transcription issue from a designed probability.

Modifiers and table selection

Some rules add a modifier to the roll before selecting a row. Others use the raw roll and apply the modifier after the table result. These operations are not equivalent. A result at the bottom or top of the table may also be capped, wrapped around, or rerolled. State the order and the boundary behavior in the entry.

Tables as editorial data

When a table is transcribed, preserve its headings, range notation, and source edition. A small change from “1–5” to “1–6” changes the weighting, while a missing row can make some rolls impossible to interpret. If a table has been updated, identify the version and keep older versions distinguishable rather than merging their ranges.

Accessibility and usability

A table should be readable without relying only on color, tiny type, or decorative symbols. Give results clear labels and explain uncommon abbreviations. For symbol-based tables, include a text legend. These are presentation choices, but they also reduce interpretation errors when a community member checks or corrects the record.

Documenting a random table

1. Identify the die, dice expression, or randomizing method.
2. Copy or summarize the range boundaries without changing their meaning.
3. State how zero, 00, maximum rolls, ties, and invalid results are handled.
4. Explain modifiers, rerolls, caps, wrapping, and weighted entries.
5. Link the official rules source and give a short worked example.

Worked example

Suppose a d20 table assigns 1–10 to “common,” 11–17 to “unusual,” and 18–20 to “rare.” Under a fair d20 model, the three categories are not equally likely because they contain 10, 7, and 3 outcomes. That conclusion concerns the table model; a physical die test would be a separate question.

Related DICEWIKI pages

Continue with dice mechanics, dice modifiers, percentile dice, and dice probability distributions.

Sources and editorial notes

1. D&D Beyond Basic Rules: Playing the Game, for official examples of random tables, percentile rolls, and dice expressions.
2. OpenStax Algebra and Trigonometry: Probability, for the relationship between outcome counts and probabilities.
3. DICEWIKI editorial taxonomy, for preserving table boundaries and separating a table model from physical-die behavior.