Dicelab

D&D Dice Roller & Probability Calculator

Advanced dice notation with advantage, critical hits, and D&D Beyond integration.

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Import D&D Beyond character

Roll dice with modifiers: 2d20 adv + 5, 1d100, or 3d8 + 2.
Use filters with spaces: 4d6 dl 1, 6d6 kh 3, 5d4 rr 1, 4d6 ro 1, or 2d20 dis.
Abbreviations: adv/dis (advantage/disadvantage), kh/kl (keep high/low), dh/dl (drop high/low), rr (reroll matching results), and ro (reroll matching results once).
Elven Accuracy (triple advantage): when you have advantage on an attack, roll three d20s and keep the highest, e.g. 3d20 kh 1 attack + 7.
Mark attack rolls by adding attack to a d20 expression to enable crit tracking. Attacks crit on a natural 20 by default and apply oncrit double_dice unless you override them with ranges like crit19..20 or modes like oncrit max_second_dice and oncrit double_all; crits only apply when paired with attack, and auto-hit logic uses the kept d20 after advantage or disadvantage.
Branch with ternary logic: condition ? then : else treats non-zero as true and defaults the missing else side to 0.
Repeat expressions with the caret operator: 1d6 ^ 3 rolls 1d6 three times and adds the results; the right side must be a non-negative number.
Assign variables once and reuse them across cells: let base = 2d8 + 3 then reference with base + 1d4.
Create aliases for quick reuse: let smite = 2d8 then roll smite + 1d6 in any cell.
Analyze probability mass functions with analyze 3d6 or comma-separated inputs like analyze 1d4 + 2, smite to view means, ranges, and quantiles.
Import a D&D Beyond character by entering its numeric ID (or share link) above and pressing Import.
Reset context to clear aliases and logs, or start fresh with the New notebook button.
Toggle per-cell logs with Hide/Show log to keep the view minimal while you work.

Ctrl/Cmd + Enter evaluates the focused cell

Rolls & results

Add roll breakdowns and group totals.

Off: No extra details saved.
Results: Show successes like includes or imports.
Rolls: Add roll results and grouped totals.
Everything: Also show assignments and rule breakdowns.

No aliases yet. Define one with let name = value.

D&D Dice Roller & Probability Calculator

Using the notebook

Simple Dice Roller Mode

Result

Examples

Notebook

Aliases