What is dice.run?

Updated

dice.run is a browser-based dice roller for tabletop RPGs and game design. It parses standard dice notation, rolls with a full audit trail, and shows the exact probability distribution — mean, range, and the full curve — for whatever expression you type. It fits you if you want to check the odds behind a roll, not just get a number.

What it actually does

Three things, and they reinforce each other:

  • Parses standard notation. You enter a dice expression and it reads it the way a tabletop player would write it. The site's own example is Attack + damage with crit on a 20, and it also supports a roll mode switch for normal / advantage / disadvantage.
  • Rolls with an audit trail. Each roll is recorded rather than just displayed, so you can trace what happened instead of trusting a single output.
  • Analyses the distribution. As you type, the exact odds appear — mean, range, and the full distribution. This is the part that separates it from a plain random-number roller.

Where the probability view helps

If you are designing a mechanic, the distribution is the answer to "is this swingy or consistent?" A single d20 is flat: every face is equally likely, so the mean tells you little about typical results. Summing dice (say, several dice added together) produces a curve clustered around the middle, which changes how a mechanic feels at the table even when the mean is identical.

The site frames this directly in its heading: Roll dice. Know the odds. The distribution panel is the "know the odds" half.

Studio: authoring dice programs

Beyond one-off rolls, dice.run has a Studio for authoring dice programs with live distributions. The site describes it as: Author dice programs with live distributions. This is aimed at game design work — you define the roll logic, and the distribution updates as you build it, so you can see the consequences of a change immediately.

Community packs

There is a Community picks section with importable packs. The site lists a D&D 5e (2024) pack, described as grouping every D&D 5e (2024) example by what you are trying to compute:

  • Attack rolls and damage in one place
  • Saves in another
  • Class-feature one-offs kept separate
  • Multi-attack as an array
  • Attack + damage with crit on a 20
  • Roll mode switch — normal / advantage / disadvantage

The pack shows 7 imports total and is credited to dicerun. A Browse all link leads to the wider set of community rolls and packs.

When to use it, and when not to

Use dice.run when Look elsewhere when
You need the probability distribution, not just a result You only want a quick random number with no analysis
You are checking whether a homebrew mechanic is too swingy You need a full VTT with maps, tokens, and combat tracking
You want a record of what was rolled You need persistent campaign logs tied to a character sheet
You are prototyping dice logic in Studio You want a physical-dice feel with 3D animation

Getting started

  1. Open dice.run.
  2. Enter a dice expression in the input above the distribution panel. The exact odds — mean, range, and full distribution — appear as you type.
  3. Roll to get a result with its audit trail.
  4. Switch roll mode if you need normal, advantage, or disadvantage.
  5. Open Studio if you want to author a dice program with a live distribution.
  6. Browse Community picks to import a pack such as D&D 5e (2024) instead of writing expressions from scratch.

The Docs link is described as the full reference for the dice expression grammar — worth reading before writing anything complex, since the grammar is what determines which expressions parse.