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Dice stats

Check odds like “2d6+3 ≥ 10” with a single dice expression. Smaller expressions use an exact calculation (Exact), and larger ones switch to simulation (Sim) automatically, with a distribution chart and shareable cards.

Randomness prefers crypto.getRandomValues, and all processing stays in your browser. Inputs and share cards are not sent to any server.

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Expression & method

Supports NdS +/- K (e.g., 2d6+3, d20, d%). Up to 200 dice and sides 1–1000. Uppercase D and spaces are normalized.

In Auto, expressions with a small number of possible totals use an exact calculation (Exact), and wide-range expressions use a simulation (Sim). If you are unsure, leaving it on Auto is recommended.

Higher counts give smoother results but take more time. Applies to Sim mode only.

Presets
  1. 1) Enter or tap a preset. Try 2d6+3 or d20+5.
  2. 2) Pick a method. Auto is recommended. Exact (exact calculation) works well for small expressions, and Sim (simulation) for larger or DC-planning cases.
  3. 3) Read the result. Success odds, mean/SD, modes, and histogram update instantly.

Success condition & odds

Success probability

P(total ≥ 10) = —

Sim is shown as an estimate. Inputs outside the support are normalized automatically. Here, total means the sum of all dice.

Key stats & modes

Minimum
—
Smallest reachable total
Maximum
—
Largest reachable total
Mean
—
Expected value (Exact) or sample mean (Sim)
Standard deviation
—
How much the totals vary
Modes (top 3)

Distribution (histogram)

When the total range is wide, values are grouped automatically into up to 60 bars.
Minimum and maximum totals are labeled automatically. A numeric summary is shown below so you can read the distribution without relying only on the chart.
Value / range Probability Note

Share & copy

History

How to use & FAQ

Useful for DC checks or build planning: stay in the browser, switch between exact calculation (Exact) and simulation (Sim), and see both odds and spread at a glance.

Which dice notation is supported?

NdS +/- K such as 2d6+3, d20, or d% is supported. Up to 200 dice per roll and sides between 2 and 1000. Uppercase D and spaces are normalized automatically.

How do Exact and Sim switch?

Auto uses Exact when total dice are small and the support size is within 6000; otherwise it switches to Sim. Even in Exact mode, very wide expressions fall back to Sim. All calculations run entirely in your browser.