Dice Probability for Beginners

Each fair side has the same chance

A normal six-sided die has six possible results. Each side has a 1 in 6 chance on one fair roll. Rolling a 6 now does not make a 6 less likely on the next roll. Each roll starts a new event.

More dice create more combinations

Two six-sided dice can make totals from 2 through 12. Those totals are not equally likely. There is only one way to make 2: both dice show 1. There are six ways to make 7, such as 1 and 6 or 3 and 4. That is why 7 appears more often than 2.

Modifiers change the total, not the roll

In many games, a modifier is added after the dice are rolled. If a d20 shows 12 and the modifier is +3, the final total is 15. The die still had the same chance to show each face.

Advantage and disadvantage

Some games roll two d20s and keep one. Advantage keeps the higher die, so high results become more common. Disadvantage keeps the lower die, so low results become more common. This is different from adding a fixed modifier.

Try a simple experiment

Open the Dice Roller. Roll one d6 ten times and record the results. Then roll it 100 times. The larger set will often look closer to an even split, but it does not have to be exact.

Chance is not a promise

Probability describes what tends to happen over many trials. It does not promise a certain result in a short game. Streaks and surprising rolls are normal.

You can compare this with two-outcome chance in the coin flip probability guide, or use the Random Card Generator to explore a deck.