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 2d100 page 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.
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. 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.
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?
Exactly 1.00%, or 1 in 100. Every face on a fair d100 is equally likely, so a 100 is no rarer than a 7.
What is the average roll on a d100?
50.5. That is the midpoint of 1 and 100, and it is worth knowing because the average of a die is always (sides + 1) divided by 2. Over many rolls your results converge on it, but any single roll tells you nothing.
Does rolling with advantage change the odds of a 100?
Advantage is a d20 mechanic, but the maths applies to any die. Rolling two d100 and keeping the higher would raise your chance of a 100 from 1.00% to 1.99%.
Is this d100 roller actually random?
Every roll comes from the Web Crypto API rather than Math.random, and uses rejection sampling to discard values that would skew the result. A plain modulo of a random number is biased when the range does not divide evenly, which for a d100 would quietly favour the low faces.