10-Sided Dice Roller (d10)

Roll one or more virtual 10-sided dice and see the odds: the actual rolled total, the expected average, the possible range, and the probability of hitting a chosen target sum.

Quick Facts

Method
Each face 1–10 has probability 1/10; sums use exact convolution counting
A single d10 averages 5.5; N dice average 5.5 × N.

Your Results

Calculated
Rolled total
-
Random roll of your dice + modifier
Expected (average) total
-
5.5 × dice + modifier
Possible range
-
Minimum to maximum total
P(total = target)
-
Odds of exactly the target sum

Ready

Set the number of dice and press Roll & Calculate.

Understanding the 10-Sided Die (d10)

A 10-sided die, or d10, is a pentagonal trapezohedron with ten faces, numbered either 1 through 10 or 0 through 9. It is one of the seven standard polyhedral dice used in tabletop role-playing games such as Dungeons & Dragons, and it doubles as a percentile tool. This roller simulates a fair d10 and computes the exact odds behind the roll, so you can see not just what you rolled but how likely that result was.

The single-die probability

A fair d10 has ten equally likely outcomes, so each face has probability P = 1/10 = 0.10 = 10%. There is nothing special about any particular number: rolling a 7 is exactly as likely as rolling a 1 or a 10. The distribution of a single die is uniform — a flat line where every value carries the same 10% chance.

The average roll

The expected value of one d10 (numbered 1–10) is the mean of its faces: E = (1 + 2 + … + 10) / 10 = 55 / 10 = 5.5. Equivalently, for any fair die numbered 1 to k, the mean is (1 + k) / 2. For N ten-sided dice the expected total is simply 5.5 × N — so two d10 average 11, three average 16.5, and ten average 55.

Adding dice: sums are no longer uniform

When you roll more than one d10 and add them, the totals stop being equally likely. With two d10, the total ranges from 2 to 20, but there are 100 equally likely (die A, die B) combinations. The extreme totals happen only one way each (2 = 1+1, and 20 = 10+10), while the middle total of 11 can be made 10 different ways (1+10, 2+9, …, 10+1). So P(sum = 2) = 1/100 = 1%, while P(sum = 11) = 10/100 = 10%. This roller counts those combinations exactly by convolution rather than by simulation, so the probabilities are exact fractions, not estimates.

Percentile dice (d100)

Two d10 are commonly used together as percentile dice: one die (often marked 00, 10, 20 … 90) gives the tens digit and the other gives the units digit, producing a number from 00 to 99, with 00 conventionally read as 100. That gives 100 equally likely outcomes, each with probability 1/100 = 1%. Note this is different from summing two d10 — reading digits keeps the outcomes uniform, while adding them does not.

Common reference values

  • One d10: range 1–10, each face 10%, average 5.5.
  • Two d10 (2d10), summed: range 2–20, average 11, peak total 11 at 10%.
  • Three d10 (3d10): range 3–30, average 16.5, peak total at 16 and 17.
  • Percentile (d100): range 1–100 (or 0–99), each value 1%, average 50.5.

Frequently Asked Questions

What are the odds of rolling a specific number on one d10?
A fair 10-sided die has ten equally likely faces, so every result has probability 1/10 = 0.10, or 10%. This holds for each individual face whether the die is numbered 1–10 or 0–9.
What is the average roll of a 10-sided die?
For a d10 numbered 1 through 10, the expected value of a single roll is (1 + 10) / 2 = 5.5. For N dice the expected total is 5.5 × N, so two d10 average 11 and three d10 average 16.5.
How do you roll percentages with d10 dice?
Roll two d10 as percentile dice: one die is the tens digit and the other the units digit, giving 00–99 (with 00 usually read as 100). That produces 100 equally likely outcomes, each with probability 1/100 = 1%. This is different from summing two d10, whose totals are not equally likely.
Is this roller fair, or is it weighted?
It is fair. Each face is drawn with equal 1/10 probability using the browser's random number generator, and the listed odds are computed exactly by counting combinations — no face or total is favored.

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