Dice Core notation

Choose a roll type

Every topic below has detailed rules and examples that open directly in the playground.

Fundamentals	Modifiers	Advanced and systems
Numeric, percentile, and Fudge dice	Keep and drop	Groups
Arithmetic and functions	Reroll and unique	Multiple rolls and comments
Comparisons on this page	Explosions	Mixed batches
	Targets and criticals	Fate
	Min, max, and sort	Vampire V5
	Pool, adv, and dis	Assimilation
	Step	Daggerheart

Expression shape

NdX rolls N dice with X sides; operators and functions build expressions. Modifiers are die suffixes: 4d6kh3. A braced list forms a group: {d8,d10}kh1. N# repeats one formula; ; splits a mixed batch, including special systems. Compact notation is conventional, but input may contain whitespace.

2d20+5
4d6kh3
{d8,d10}kh1
2#d20+5
d20+5; v5(7,3,4)

Compare points

Conditional modifiers accept =, !=/<>, <, <=, >, and >= followed by a numeric literal, signed if needed. r<3 rerolls 1 or 2 on d20; !>=5 explodes on 5 or 6 on d6; >=8f=1 counts successes and failures. Immediately after a die, ! starts an explosion, so d6!=3 means “explode on 3”; for a “not equal to 3” target use d6<>3.

Normalization shortcuts

d becomes d20; f becomes 4dF; 2f becomes 2dF; ei6 becomes !>=6; km becomes kl1; k becomes k1. -pool(N) becomes pool(-N), while +step(N) becomes step(+N). normalizeRpgDiceNotation() returns normalized text; inspectRpgDiceNotation() validates without consuming RNG.

import { normalizeRpgDiceNotation, inspectRpgDiceNotation } from '@erpg/dicecore/core'
console.log(normalizeRpgDiceNotation('d + 2f')) // d20+2dF
console.log(inspectRpgDiceNotation('4d6kh3').isValid) // true

Runtime modifiers follow a fixed order: min, max, explode, reroll, unique, keep, drop, target, critical success, critical failure, and sort. Structural pool, adv, dis, and step resolve first. If a modifier kind appears more than once, the last one wins.

Try the examples

Try 4d6kh3 · Try d6!2>=5 · Try d20+5;v5(7,3,4)