Dice Calculator
Exact D&D dice probabilities: expected damage vs AC, save-for-half, advantage comparison, and full outcome curves — not just a roller.
Attack builder
Query
Examples
6.40
normal d20 +5 vs AC 15 · 2d6+4 / crit 4d6+455.0%
5.0%
41.1%
Outcome distribution
Attack stats
- Hit / fail damage avg: 11
- Crit damage avg: 18
- Miss / success rate: 45.0%
Dice Cove’s dice calculator is an exact probability and expected-damage tool for D&D and tabletop RPGs. Build an attack or save, or type any NdS notation, and read the full outcome curve instantly — no Analyze button, no sign-up.
Why this beats a basic dice calculator
- Live exact distributions (not Monte Carlo estimates for common pools)
- Attack builder with AC, crit range, advantage, elven accuracy, and Halfling Luck
- Save builder with DC and half-or-zero on success
- Hit / crit / miss breakdown and expected damage including misses
- Compare advantage vs normal (or any two dice expressions)
- Percentiles, stdev, P(≥ target), cumulative charts, and shareable URLs
How to use the dice calculator
- Pick Attack, Save, or Dice mode.
- For attacks: set bonus, AC, damage (e.g. 2d6+4), and crit damage (4d6+4).
- Toggle advantage or open Compare to see how much advantage is worth.
- Set a target value to read P(≥ target) on the distribution.
- Share the URL — your setup is stored in the hash.
Dice average cheat sheet
- 1d4 avg 2.5 · 1d6 avg 3.5 · 1d8 avg 4.5
- 1d10 avg 5.5 · 1d12 avg 6.5 · 1d20 avg 10.5
- NdS average = N × (S + 1) / 2 (before modifiers or keep/drop)
- 8d6 (Fireball) averages 28 · 4d6dl1 ability scores use drop-lowest
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Single-die rollers
- Roll a d4
- Roll a d6
- Roll a d8
- Roll a d10
- Roll a d%
- Roll a d12
- Roll a d20
- Full D&D dice roller — visual 3D rolls
- Coin flip simulator
Canonical URL: /dice-calculator/
Frequently asked questions
How is this different from a dice roller?
A roller shows one random outcome. This calculator computes the exact probability distribution — average, hit chance, crit chance, percentiles, and P(≥ target) — so you can plan attacks and spells before you roll.
How does a dice average calculator work?
For a fair NdS roll with no keep/drop rules, the average is N × (S + 1) / 2. Example: 8d6 averages 28. Keep/drop, advantage, crits, and AC checks change that; this tool enumerates the full distribution instead of guessing.
Can it calculate expected damage against AC?
Yes. Use Attack mode: set attack bonus, target AC, damage dice, crit range, and advantage. The result includes hit chance, crit chance, and expected damage (counting misses as 0).
Does it support save-for-half spells like Fireball?
Yes. Save mode models d20 + save bonus vs DC, then applies full damage on a fail and half (rounded down) or zero on a success.
What notations are supported?
Standard NdS with modifiers and keep/drop: 8d6, 2d6+4, 2d20kh1, 4d6dl1, and similar. Attack and Save builders handle AC, DC, crits, advantage, elven accuracy, and Halfling Luck without cryptic expressions.
Where do I go to actually roll dice visually?
Open the D&D dice roller for 3D rolls and a session log. Dedicated pages like Roll a d20 or 8d6 are also available for one-click rolling.