DND Dice Roller: Notation, Advantage and Repeats

How to use the dnd dice roller

1. Type your dice expression in the Notation field, such as 2d6+3 or 4d6kh3.
2. Select Advantage or Disadvantage if you are rolling a d20 check.
3. Set the Repeat count to roll the same expression multiple times, useful for generating ability scores.
4. Click Roll to see each individual die, any kept or dropped values, modifiers and the total.

Understanding dice notation

Dice notation follows the pattern NdM+K. N is the number of dice to roll, M is the number of sides on each die and K is an optional modifier added after the dice are summed. For example, 2d6+3 means roll two six-sided dice, add their faces together, then add 3. If N is omitted it defaults to 1, so d20 is the same as 1d20.

The kh (keep highest) and kl (keep lowest) suffixes let you drop dice before summing. 4d6kh3 rolls four six-sided dice and keeps only the three highest results, which is the standard method for generating D&D ability scores. The dropped dice are listed in the output after the word dropped so you can verify the result. Spaces in the notation are ignored, so 2d6 + 3 works.

How advantage and disadvantage work

In fifth edition D&D, advantage means you roll two d20s and use the higher number. Disadvantage means you roll two d20s and use the lower number. This dnd dice roller applies that rule automatically when you select the corresponding option and your base die is a d20. Modifiers are applied after the correct die is chosen.

For instance, with advantage and a +5 modifier, the tool rolls two d20s, picks the higher value, adds 5 and displays both original rolls so you can see what was discarded. Advantage and disadvantage do not stack: if you have both, they cancel out to a normal roll, so leave the mode on None. The mode only works with a single d20, so an expression such as 4d20 returns an error instead of silently rolling a pair.

Common dice expressions reference

Natural 20s and natural 1s

A natural 20 occurs when the physical d20 lands on 20 before any modifiers are applied. In most D&D rulesets, a natural 20 on an attack roll is an automatic hit and often a critical hit, doubling the damage dice. A natural 1 is typically an automatic miss on attacks. This dice roller for dnd flags these outcomes in the note field whenever the base die is a d20, regardless of modifiers.

Critical hits usually mean you roll all damage dice twice. For example, a dagger dealing 1d4+2 damage would deal 2d4+2 on a critical hit. You can simulate this by changing your notation to double the dice count.

Fairness and randomness

Physical dice can be biased due to manufacturing imperfections. An online dnd dice roller uses your device's cryptographic random number generator via crypto.getRandomValues, which produces uniformly distributed integers. Each face of every die has exactly the same probability of appearing.

Because the computation happens locally in your browser, no server influences or records your rolls. You get the convenience of a digital tool without trusting a remote machine to be fair.

Worked examples