Pick a die from d4 to d100, set how many to throw, add your bonus, then roll. Type notation like 2d6+3 or 1d20 adv if you know the shorthand. A face tally builds up under the tray, so a long session shows you the spread, not a single lucky number.
Press Roll or tap the space bar.
Tabletop players write rolls as count, d, sides. 3d8 means three eight-sided dice added up. A plus or minus at the end adds a flat bonus. The notation box reads every row below.
| Type | What happens | Range | Average |
|---|---|---|---|
1d6 | One six-sided die | 1 to 6 | 3.5 |
2d6 | Two d6 added together | 2 to 12 | 7 |
1d20+5 | One d20 plus a flat 5 | 6 to 25 | 15.5 |
1d20 adv | Roll the d20 twice, keep the higher face | 1 to 20 | 13.83 |
1d20 dis | Roll twice, keep the lower face | 1 to 20 | 7.18 |
4d6dl | Four d6, set the lowest aside | 3 to 18 | 12.24 |
3d6! | Exploding d6, a 6 rolls again and adds on | 3 and up | 12.6 |
1d100 or 1d% | Percentile roll | 1 to 100 | 50.5 |
Spaces and capital letters get ignored. The roller takes 1 to 20 dice with 2 to 1000 sides, so a d3 or a d30 works too. Odd sizes show up as round tokens on the tray.
One die is flat. Every face of a d6 has a 1 in 6 chance. Add a second die and the odds bend into a hill. Six of the 36 combinations make 7 (1+6, 2+5, 3+4 and their reverses), while one combination makes 2 and one makes 12.
Catan prints the 6 and 8 tokens in red for this reason. They sit one step off the peak and come up 5 times in 36. Set the roller to 2d6, roll fifty times, and watch the face tally and your average settle near 7.
The three special modes come from tabletop games, and each one moves the average in a predictable direction.
Fifth edition D&D rolls two d20 and keeps the better face, or the worse one under disadvantage. Here every die in the roll gets a second throw, and the discarded face shows crossed out under the die. Advantage nearly doubles your odds of a natural 20, from 5% to 9.75%.
The classic ability score method. Roll 4d6, set the lowest die aside, add the other three. Repeat six times for a full stat line. The dropped die stays on the tray, faded, so everyone at the table sees nothing got hidden. Straight 3d6 averages 10.5.
Savage Worlds calls this acing. A die showing its top face rolls again and adds the new face, so a d6 has no ceiling. The note under the die shows the chain, for example 6+6+2. The roller stops a chain after 50 rerolls, a length no fair die reaches.
Each face comes from crypto.getRandomValues, the random source browsers use for encryption keys, not Math.random. A plain remainder on a random number gives low faces a tiny edge whenever the range does not divide evenly. The roller throws away any draw from the leftover slice and draws again, so every face of a d6, d20 or d7 has an exact equal share.
Nothing goes to a server. The roll happens on your device, and the page keeps rolling with no connection once loaded.
Physical dice are less even than most players assume. Drilled pips remove more plastic from the 6 face than from the 1 face, so cheap dice lean slightly toward landing 6-up. Casino dice fill their pips with paint of matching weight to cancel this out.
Yes. Faces come from the browser crypto random source with rejection sampling, so no face gets a bias from rounding. The face tally under the tray lets you check: roll a d6 600 times and each bar lands near 100, usually within 20 either way.
Type the roll into the notation box and press Enter, or pick d20, set How many to 1 and Modifier to 5, then press Roll. The box also takes adv, dis, dl for drop lowest, and an exclamation mark for exploding dice, for example 1d20+5 adv or 3d6!.
Type 4d6dl and roll six times. Each roll sets the lowest die aside and adds the other three, giving a result from 3 to 18 with an average of 12.24. The log keeps all six results in order.
The long-run average for the current setup, worked out exactly, modifier included. Your average sits beside the Expected figure. Over a handful of rolls the two drift apart. Over a few hundred they close in.
Exploding mode added a reroll. Once a d6 passes 6 the face has no pip layout, so the tray shows the running total and the chain sits under the die.
Only in the open tab. The log holds the last 12 rolls and the tally covers the current die type. Changing the setup resets the averages. Refresh and everything clears. Copy result puts the last roll on your clipboard as plain text.
