Single die
Roll a d100
A 100-sided die, rolled in your browser. Every face has an equal 1.00% chance, which works out to 1 in 100.
The odds on a d100
A single die is flat: no total is more likely than any other. The curve only appears once you roll more than one, which is what the odds calculator is for.
- Lowest
- 1
- Highest
- 100
- Average
- 50.50
- Each face
- 1.00%
- Odds
- 1 in 100
Every bar the same height. That flatness is the whole point of a single die: 1.00% per face, no favourites.
What a d100 is for
Percentile rolls. Loot tables, wild magic surges, and anything a referee wants to leave to fate.
Flat, and deliberately so
A d100 is almost never a hundred sided object. It is two ten sided dice read as digits, or a single d10 rolled twice, and physical hundred sided dice exist mainly as novelties because they behave more like marbles than dice and take an uncomfortable amount of time to stop.
The point of a percentile roll is that it is uniform and readable as a percentage without any conversion. If a table says an outcome happens 17% of the time, you roll and check whether you got 17 or under. No arithmetic, no lookup, and the granularity is fine enough to encode long lists of rare results. That is why loot tables, random encounters and wild magic effects use percentiles rather than a curved roll: the designer wants to assign exact weights, and a flat die is the only one that lets them.
It is also why percentile systems feel different to play than curved ones. There is no regression to the middle and no such thing as a typical result. Every outcome on the table is exactly as likely as its listed weight, all the way out to the one in a hundred entries at the bottom.
Hitting a target number
What a flat d100 beats, and how much two-dice advantage moves it.
| Need | Flat | Advantage | Disadvantage |
|---|---|---|---|
| 2+ | 99.0% | 100.0% | 98.0% |
| 12+ | 89.0% | 98.8% | 79.2% |
| 22+ | 79.0% | 95.6% | 62.4% |
| 32+ | 69.0% | 90.4% | 47.6% |
| 42+ | 59.0% | 83.2% | 34.8% |
| 52+ | 49.0% | 74.0% | 24.0% |
| 62+ | 39.0% | 62.8% | 15.2% |
| 72+ | 29.0% | 49.6% | 8.41% |
| 82+ | 19.0% | 34.4% | 3.61% |
| 92+ | 9.00% | 17.2% | 0.810% |
How to use this roller
Tap the die or press the roll button. To roll several at once, change How many, and the chart above redraws to the distribution you are actually rolling. To add a bonus, put it in Modifier: entering 3 turns a d100 into 1d100+3. Negative numbers work for penalties. The keyboard shortcut is R. After a roll, Copy link gives you a URL that shows exactly that result to whoever opens it.
Nothing is stored on a server and no account is needed. The page works offline once loaded, which matters if the venue has poor signal.
Common questions about the d100
What are the odds of rolling a 100 on a d100?
The odds of rolling a 100 on a d100 are exactly 1.00%, or 1 in 100. Every face on a fair d100 is equally likely, so a 100 is no rarer than any other number.
How do you read percentile dice?
Roll two d10s, one marked in tens (00, 10, 20 to 90) and one in units (0 to 9), and add them. A 70 and a 3 is 73. A 00 and a 5 is 5. A 00 and a 0 is 100 rather than 0, which is what makes the range 1 to 100. If both dice are numbered 0 to 9, agree on which colour is the tens before you roll.
Is a d100 roll 1 to 100 or 0 to 99?
Most games read percentile dice as 1 to 100, with double zero counting as 100, and that is what this roller does. A few systems read them as 00 to 99 instead. The odds are the same either way, exactly 1% per result; only the label on the bottom result changes.
What is the average roll on a d100?
The average roll on a d100 is 50.5. That is the midpoint of 1 and 100, and the average of any die is always (sides + 1) divided by 2. Over many rolls your results converge on it, but any single roll tells you nothing.