RPG Dice Roller

🕹️ How to play

1. How to roll: The box starts at 1d20 — just press Roll. To change dice, tap the die keys (d4, d6, d8, d10, d12, d20, d100). Right after a roll, a die key starts a fresh pool; tapping the same key again adds another die, so two taps on d6 gives 2d6.
2. Add modifiers and roll with advantage: Use −1 / +1 to change the trailing modifier — three taps on +1 is +3. Adv turns 1d20 into 2d20kh1 (roll two, keep the higher), Dis turns it into 2d20kl1, and tapping again goes back to 1d20. Every key writes the notation back into the box so you learn it as you go.
3. Type dice notation: Type 2d6+3, 1d8+1d6 or 4d6kh3 and press Enter or Roll. Text after a space becomes a label, like “1d20+5 attack”. Common dialects work too: a /r or .r prefix, k/h/l shorthands and d%. A typo never rolls a guess — the line under the box points at the character and offers a fix to tap.
4. Percentile skill checks: Switch to Percentile, enter a skill value (1–99), add bonus or penalty dice with the stepper and press Check. You see the units die and every tens candidate: bonus dice keep the lowest result, penalty dice the highest, and the result is graded critical, extreme, hard, success, failure or fumble.
5. Save and re-roll: After a roll, tap the star on the result and name it (say “Longsword”) to add it to the favorites bar for one-tap rolls. History keeps your last 100 rolls — tap any to roll it again — and Session stats charts how often each face came up against the expected line.

📖 Rules & variants

Notation: NdS rolls N dice with S sides and adds them; N defaults to 1 (d20 = 1d20), S runs 2–1000 and d% means d100. Combine terms with + and − only, modifiers up to 9999. A roll may start negative (-1+1d20) and totals can go below zero — nothing is clamped to 1.

Keep and drop: khN keeps the highest N dice, klN the lowest N, dlN drops the lowest N and dhN the highest N; N defaults to 1, and k/h mean kh while l means kl. Ties keep the die rolled first. Dropped dice are greyed out and struck through and never count toward the total.

Advantage and disadvantage: advantage is 2d20kh1 (roll two d20, keep the higher), disadvantage is 2d20kl1. Advantage averages about 13.8 versus 10.5 for a single d20. It is not the same as 2d20, which adds both dice for a 2–40 range.

Repeat rolls: prefix N# (1–10) to roll the same thing several times — 6#4d6kh3 rolls a full set of six ability scores, each shown separately and never added together. Limits: 200 dice, 20 terms and 120 characters per roll.

Natural 20 and natural 1: when a roll has exactly one d20 term keeping one die, a kept 20 is flagged as a natural 20 and a kept 1 as a natural 1, regardless of modifiers. A single d100 also shows its tens + units reading, with 100 read as 00 + 0.

Percentile checks: one units die (0–9) plus 1 + N tens dice (00–90); each tens die with the units die is a candidate and 00 + 0 counts as 100. Bonus dice keep the lowest candidate, penalty dice the highest, up to two net. A 1 is a critical; with skill under 50 any 96+ is a fumble, otherwise only 100. Then ≤ skill/5 is an extreme success, ≤ skill/2 a hard success and ≤ skill a success.

Not supported yet: exploding dice (!), success-counting pools (>=), rerolls (r1), Fate dice (dF), multiplication, division and brackets. These are rejected with the position marked — never silently reinterpreted.

❓ FAQ