2d6+3 means roll two six-sided dice, add them together, then add 3. The result ranges from 5 (two 1s, plus 3) to 15 (two 6s, plus 3), averaging 10. Upfront and honest about our own tool: our dice roller handles one or two six-sided dice, which covers 1d6 and 2d6, nothing more, no d20, no modifiers, no polyhedral set.
The formula: XdY+Z
X is how many dice you roll. d just means “dice.” Y is how many sides each one has. Z, if present, is a flat number added (or subtracted) after all the dice are added together. Worked examples: 1d6 is one six-sided die, no modifier. 2d6 is two six-sided dice, summed. 3d8+2 is three eight-sided dice, summed, plus 2. 1d20+5 is one twenty-sided die plus 5. 1d4−1 is one four-sided die, minus 1, and yes, the modifier can be negative.
Read the notation left to right and it decodes itself: the number before the “d” tells you how many separate dice to physically pick up and roll, the number after it tells you which die from the set to reach for, and anything after a plus or minus sign happens once, after every die has already been rolled and added, never per-die.
Working out the average of any roll
A single die averages (Y+1) ÷ 2. That gives 1d4 = 2.5, 1d6 = 3.5, 1d8 = 4.5, 1d10 = 5.5, 1d12 = 6.5, 1d20 = 10.5. For a full XdY+Z roll, the average is X × (Y+1)/2 + Z. Worked: 2d6+3 = 2 × 3.5 + 3 = 10. 8d6 = 8 × 3.5 = 28.
The seven-dice set, and what each one is for
The classic tabletop set: d4 (four-sided, a small pyramid, common for minor weapon damage), d6 (six-sided, the familiar cube, general-purpose rolls), d8 (eight-sided, mid-tier weapons and effects), d10 (ten-sided, numbered 0-9, general rolls and one half of a percentile pair), a second d10 marked in tens (00, 10, 20… 90) specifically for percentiles, d12 (twelve-sided, less common, certain weapon and class effects), and d20 (twenty-sided, the central roll for skill checks, attacks and saving throws in most tabletop role-playing games).
Most boxed sets include exactly these seven, sold together as a matched set in a small pouch or tin, since between them they cover nearly every roll a typical tabletop game asks for without needing a specialty die for anything beyond percentiles. The two d10s look identical in shape, distinguished only by which one is printed with the tens markings, worth checking before a game starts if a set is unfamiliar.
Percentile dice (d100 / d%)
Two ten-sided dice produce a number from 1 to 100 together, one marked in tens (00, 10, 20, up to 90), the other in units (0 through 9). Read them together, a tens-die 30 with a units-die 4 reads as 34. The one genuine edge case, and the part people get wrong: both dice showing zero, 00 and 0, is read as 100, not 0, since a roll of zero on a percentile check has no meaning.
4d6 drop lowest, the ability-score roll
Roll four six-sided dice, discard the single lowest result, and sum the remaining three. Computing the true average across all 1,296 possible combinations of four d6 rolls gives 12.24, meaningfully higher than a plain 3d6 roll’s flat 10.5 average, dropping the lowest of four dice skews the result upward by design, which is exactly why this method produces stronger ability scores than rolling three dice outright.
Advantage and disadvantage
Roll two d20s and take the higher result for advantage, or the lower for disadvantage. Computing the expected value of the higher of two d20s across all 400 possible pairs gives 13.825, a bit over 3 points above a plain 1d20’s flat 10.5 average. Disadvantage works out to the mirror image, 7.175, a bit over 3 points below. Advantage and disadvantage both help most in the middle of the range, a check that was already a near-certain success or failure on a flat roll doesn’t shift much either way, since the die most likely to be picked as the max or min was probably going to land there regardless. A check that needs a roll of, say, 11 or higher on a flat d20 is roughly a coin-flip already, and that’s exactly where advantage’s boost matters most, a check that needed a natural 19 barely improves, since even with two dice rolled, landing on 19 or 20 at all remains rare.
Other notation you’ll see
A handful of conventions that show up in specific tools, worth recognizing even though none of these are universal standards: kh3 or kl1 (keep the highest 3, or the lowest 1, of a larger pool), r1 (reroll any 1s), ! (exploding dice, where a maximum roll triggers an extra roll added on top), and 2d6+1d4 (a mixed pool of different die types added together). Treat these as tool-specific shorthand rather than something every dice roller supports identically.
What our dice roller does
The honest section, stated plainly rather than buried: our dice roller rolls one or two six-sided dice, with a tumble animation and a big-screen total. That covers 1d6 and 2d6 exactly, and nothing past that, no d20, no polyhedral set, no modifiers, no roll history saved between sessions. For a d20 or a full seven-dice tabletop set, you’ll need physical dice or a dedicated polyhedral roller elsewhere for now. A d20 page is planned for this site, without a promised date yet, this page will link to it once it genuinely exists rather than pointing anywhere prematurely.
DUNGEONS & DRAGONS is a trademark of Wizards of the Coast; this page explains general dice notation used across many tabletop games and systems, it is not affiliated with or endorsed by Wizards of the Coast, and no rules text from any specific game is reproduced here.
FAQ
What does 2d6+3 mean?
Roll two six-sided dice, add the two results together, then add 3. The lowest possible result is 2+3=5, the highest is 12+3=15, and the average is 10.
What is a d20 used for?
A twenty-sided die, the core roll in most tabletop role-playing games for skill checks, attacks and saving throws, since a flat 1-to-20 spread with a small modifier gives a wide, easily adjustable range of outcomes.
How do you roll percentile dice?
Two ten-sided dice, one marked in tens (00, 10, 20… 90) and one in units (0-9), read together as a number from 1 to 100. Both showing zero (00 and 0) is read as 100, not 0.
What does 4d6 drop lowest mean?
Roll four six-sided dice, discard the single lowest result, and add the remaining three together. It’s the standard method for rolling ability scores in many tabletop role-playing games, and it averages meaningfully higher than a plain 3d6 roll.
Does PaperCarnival have a d20 roller?
Not yet. Our current dice roller handles one or two six-sided dice only, no d20, no polyhedral set and no modifiers. A dedicated d20 page is planned, without a promised date yet.
Need what our roller actually does today? Dice roller, free, one or two six-sided dice, no signup. For a simpler flat coin flip instead, flip a coin, or track results across a group with the online scoreboard.