What dice notation does this roller support?

It supports standard tabletop notation: NdM for N dice of M sides (for example 3d6), flat modifiers (+2 or -1), multiple groups joined with + and - (such as 1d8+3d6+4), keep/drop directives (kh, kl, dh, dl) and exploding dice with a trailing exclamation mark (3d10!). You can also list several independent expressions separated by commas.

How do advantage and disadvantage work?

Advantage in Dungeons and Dragons means rolling two d20s and taking the higher — written 2d20kh1 (keep highest 1). Disadvantage takes the lower — 2d20kl1 (keep lowest 1). The tool rolls both dice, shows them, and strikes through the one that was dropped so you can see exactly what happened.

What does kh, kl, dh and dl mean?

These are keep/drop directives. kh-N keeps the N highest dice, kl-N keeps the N lowest, dh-N drops the N highest and dl-N drops the N lowest. For example 4d6dl1 rolls four six-sided dice and drops the lowest — the classic Dungeons and Dragons ability-score method.

What are exploding dice?

Adding an exclamation mark (for example 3d10!) makes a die explode: whenever it rolls its maximum face you roll it again and add the new result, repeating until you roll something below the maximum. Exploding dice are common in systems like Savage Worlds and Shadowrun. The roller caps explosions for safety and ignores them when estimating the average.

Are the rolls genuinely random?

Yes. The roller uses the browser Web Crypto API (crypto.getRandomValues) with rejection sampling, so every face is equally likely and there is no modulo bias. This is the same source of randomness browsers use for cryptographic keys — far better than a typical Math.random shuffle.

Is my roll history private, and can I export it?

Completely private. Every roll is computed and stored in your own browser using localStorage; nothing is ever sent to a server. You can export your entire session to a CSV file (timestamp, label, notation and total) for spreadsheets or play-by-post logs, and clear the history at any time.

Dice Notation Roller

The Dice Notation Roller is a full-featured virtual dice tray for tabletop role-playing games, board games and probability experiments. Instead of clicking a single die type over and over, you type the roll the way rulebooks write it — 3d6+2, 2d20kh1+5, 4d6dl1, 1d8+3d6 — and the tool parses the whole expression, rolls cryptographically-secure dice, and shows you every result.

It is built for players who want speed and transparency at the same time. A single field accepts an entire attack-and-damage line, an ability-score array, or a tense saving throw with advantage. You see not just the total but each individual die, which dice were kept or dropped, and whether you scored a natural maximum or a dreaded natural one. Common rolls can be saved as one-tap buttons, and your whole session is logged so you can reroll, review and export later.

How it works

The roller reads standard dice notation, the compact shorthand that has been used in role-playing games for decades. The core unit is NdM: roll N dice, each with M sides. You combine units and flat modifiers with plus and minus signs, so 1d20+5 is a d20 plus five, and 2d6+1d8+3 adds two six-sided dice, one eight-sided die, and a constant three. Several independent rolls can share one line if you separate them with commas, which is handy for “to hit, then damage”.

On top of that base it understands the directives players reach for most often:

Keep highest / lowest — kh and kl. 2d20kh1 rolls two d20s and keeps the higher (advantage); 2d20kl1 keeps the lower (disadvantage).
Drop highest / lowest — dh and dl. 4d6dl1 rolls four d6s and drops the lowest, the classic ability-score generator.
Exploding dice — a trailing !. 3d10! rerolls and adds whenever a die lands on its maximum face, the mechanic behind Savage Worlds and Shadowrun.

Each roll uses the browser’s Web Crypto generator with rejection sampling, so results are unbiased and unpredictable. The live preview shows the theoretical range and average for whatever you have typed before you even roll, and the result panel breaks the outcome down die by die — dropped dice are struck through, exploded dice are flagged, and natural max or min faces are colour-coded.

Example

Suppose your rogue attacks with advantage and, on a hit, deals a longsword strike plus sneak-attack damage. You would type 2d20kh1+7 for the attack and, on a hit, 1d8+3d6+4 for the damage. The roller might show [18, 6] keep 18 giving a total of 25 to hit, then 7 + (4, 2, 5) + 4 = 22 damage with each die laid out so you can verify the maths instantly.

Notation	Meaning	Typical use
`1d20+5`	one d20 plus 5	attack or check
`2d20kh1`	two d20s, keep highest	advantage
`2d20kl1`	two d20s, keep lowest	disadvantage
`4d6dl1`	four d6s, drop lowest	ability score
`8d6`	eight d6s	fireball damage
`3d10!`	exploding d10s	Savage Worlds trait

Every figure is generated locally in your browser, stored only on your device, and never uploaded. Save the rolls you make most, build a session log as you play, and export the whole history to CSV whenever you want a record.