Rollune
XdY+Z means "roll X dice with Y sides and add Z". 2d6+3 is two six-sided dice plus 3. Suffixes change which dice count: kh/kl keep the highest/lowest, dh/dl drop them, so advantage is 2d20kh1 and ability scores are 4d6dl1.
The basic formula: XdY
Every roll starts with X d Y:
- X, the number of dice (if it's missing, it's 1)
- d, "die" or "dice"
- Y, the number of sides
| Notation | Read as | Range | Average |
|---|---|---|---|
d20 or 1d20 |
one twenty-sided die | 1–20 | 10.5 |
2d6 |
two six-sided dice, added | 2–12 | 7 |
3d8 |
three eight-sided dice | 3–24 | 13.5 |
8d6 |
eight d6 (Fireball!) | 8–48 | 28 |
d% / d100 |
percentile | 1–100 | 50.5 |
To find the average of any XdY, multiply X by (Y + 1) ÷ 2. So 3d8 averages 3 × 4.5 = 13.5.
Modifiers: +Z and −Z
A number after a plus or minus sign is a flat modifier. 1d20+5 means roll a d20 and add 5, which is how most attack rolls and ability checks look in D&D 5e. 1d6−1 subtracts one. Modifiers come from ability scores, proficiency and magic items; see ability scores and modifiers.
Mixing dice
You can add different dice together: 1d8 + 2d6 + 3 is a longsword hit with 2d6 of bonus damage and a +3 modifier. Roll each group and add everything.
Keep and drop: kh, kl, dh, dl
Many rolls throw extra dice and ignore some of them. Online rollers and VTTs write this with suffixes:
| Suffix | Meaning | Example | Used for |
|---|---|---|---|
khN (or kN) |
keep highest N | 2d20kh1 |
Advantage |
klN |
keep lowest N | 2d20kl1 |
Disadvantage |
dlN (or dN) |
drop lowest N | 4d6dl1 |
Rolling ability scores |
dhN |
drop highest N | 3d6dh1 |
Some house rules, penalties |
4d6kh3 and 4d6dl1 mean the same thing: keep three, drop one. The odds are covered in advantage and disadvantage odds and how to roll ability scores.
Other notation you'll meet
- Exploding dice (
!):1d6!means if you roll the maximum, roll again and add it. Savage Worlds uses exploding dice ("aces"). - Dice pools and successes:
6d10>=6means roll six d10 and count how many show 6 or higher (Vampire: The Masquerade style). Shadowrun counts 5s and 6s on d6 pools. - Fudge/Fate dice (
4dF): four dice with −, blank and + faces, for a result from −4 to +4. - Multiplied rolls (
×N): "roll 1d20+4 ×5" often means five separate attacks, not one big total.
Practice
Type any of these into the online dice roller (it understands XdY, +Z, kh, kl, dh, dl and d%) and watch which dice count. In the Rollune app you can save your favorites as presets.
