Dice Notation Explained: What 3d20, 4d6 and 2d6+3 Mean

By Nektarios Livitsanos · Updated September 17, 2026

Dice notation is the short code tabletop games use to say which dice to roll. Once you can read it, you can also tell at a glance how high a roll can go, what it will usually land on, and how swingy it is.

Reading NdS+M

Almost every roll you will meet follows the same pattern:

• N is how many dice you roll. If it is missing, it means one, so d20 and 1d20 are the same thing.
• d stands for "die" and separates the two numbers.
• S is how many sides each die has: 4, 6, 8, 10, 12, 20 or 100 in most games.
• +M or −M is an optional fixed number added to or taken from the total.

So 3d20 is three twenty-sided dice added together, 4d6 is four six-sided dice, and 2d6+3 is two six-sided dice plus 3. Rolls can be combined, too: 1d20+1d4+2 means a d20, a d4 and 2, all added up.

Minimum, maximum and average in ten seconds

You do not need a table to size up a roll. Three quick rules cover it:

The average works because a single die averages the middle of its faces: a d6 averages 3.5, a d20 averages 10.5. Multiply by the number of dice and add the modifier. For 2d6+3: 2 × 7 ÷ 2 + 3 = 10.

Here are the rolls people search for most, worked out. Each one opens ready to roll in our dice roller.

Why more dice means more predictable

A single die is flat: on a d20, a 1 is exactly as likely as a 10 or a 20, 5% each. Add a second die and that changes, because there are more ways to make a middle total than an extreme one. With two six-sided dice there is only one way to roll 2 (a 1 and a 1), but six ways to roll 7.

Here is the full picture for 2d6:

The more dice you add, the tighter the results bunch around the average. With 10d4 the total can be anything from 10 to 40, but the most likely single result is 25, and rolling the minimum of 10 takes ten 1s in a row, a chance of about one in a million. With 10d20, almost three rolls in four land between 85 and 125, even though the full range runs from 10 to 200.

This is why game designers use several small dice when they want steady, reliable results, and one big die when they want anything to be possible.

2d6 is not the same as 1d12

Both top out at 12, so they look interchangeable. They are not. 1d12 gives every number from 1 to 12 the same 8.3% chance. 2d6 can never roll a 1, lands on 7 twice as often as 1d12 lands on any number, and makes 2 and 12 rare. If a game says 2d6, rolling a d12 instead changes how it plays.

Rolls that keep or drop dice

Some rules roll extra dice and then ignore a few. You will see these written in several ways, and our roller shows every die separately so you can apply them yourself.

Advantage and disadvantage (2d20, keep one)

Roll 2d20 and keep the higher die for advantage, the lower for disadvantage. Some tools write this as 2d20kh1 or 2d20kl1. The effect is bigger than it looks:

4d6 drop the lowest

The classic way to generate ability scores: roll 4d6, ignore the lowest die, add the other three. The result still runs from 3 to 18, but it averages about 12.24 instead of the 10.5 you get from plain 3d6. A perfect 18 comes up about 1.6% of the time, compared with under 0.5% on 3d6. You may see it written as 4d6dl1 or 4d6kh3.

Other codes you might meet

• d% is a percentile roll, the same as d100. Tables often roll it as two d10, one for tens and one for units, with 00 and 0 read as 100.
• dF is a Fudge or Fate die with two minus faces, two blank faces and two plus faces.
• ! after a roll, as in 1d6!, means the die explodes: roll a maximum and you roll it again and add the new result.

Our roller handles plain dice and modifiers, not these special codes. For exploding dice, roll again by hand when you see a maximum.

Rolling online with GoPickaro

Type any notation into the box at the top of the dice roller and press Set & Roll. You can roll up to 10 dice at once, each with 2 to 100 sides, and add a modifier between −1000 and +1000. For bigger pools, such as 20d6, roll two groups of 10 and add the totals.

You can also save a roll as a link. gopickaro.com/dice/?roll=8d6 opens with eight d6 ready, which is handy to bookmark for a spell or attack you use every session.

Every value comes from your browser's cryptographically secure random generator at the moment you press Roll, and the animation only reveals a result that has already been chosen. The fairness page explains the method in more detail.

Frequently asked questions

What does 3d20 mean?

Roll three twenty-sided dice and add them. The total is between 3 and 60 and averages 31.5. The chance that at least one of the three shows a 20 is about 14.3%.

What does the number after the plus sign do?

It is added once to the total, not to each die. 2d6+3 is the sum of two dice plus 3, so it runs from 5 to 15.

Is an online dice roller as random as real dice?

A good one is at least as fair. Physical dice can have tiny manufacturing flaws that favour some faces, while a cryptographically secure generator gives every face exactly the same chance.

Can I subtract dice, like 1d20−1d4?

Not in our roller. Roll the two dice separately and subtract, or use a fixed modifier such as 1d20-2 if your game allows it.

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