Dice roller

How to type a roll

The box takes standard dice notation. Spaces and capital letters are fine.

Limits: up to 500 dice in a group, 20 groups, and dice of 2 to 1,000 sides. That covers a large fireball and stops a typo from freezing your phone.

What advantage and disadvantage do to your odds

Under the fifth edition rules in the System Reference Document 5.1 ("Advantage and Disadvantage"), you roll a second d20 and use the higher roll with advantage or the lower roll with disadvantage. Several sources of advantage still give you only one extra die, and if you have both advantage and disadvantage they cancel and you roll one d20.

How much is that worth? It depends on the number you need. Here are the exact chances of rolling at least each number on the die, before bonuses:

The gain is biggest in the middle. Needing an 11, advantage takes you from 50% to 75%, about the same as a +5 bonus. Needing a 20, it only moves you from 5% to 9.8%. So advantage matters most on rolls that were a coin flip to begin with.

Natural 20s and natural 1s

The roller flags a single kept d20 that lands on 20 or 1, because those faces have special rules in fifth edition. In the SRD 5.1 combat rules, a 20 on an attack roll hits no matter the target's Armor Class and is a critical hit, and a 1 always misses. On a death saving throw, a 20 brings you back with 1 hit point and a 1 counts as two failures. On ability checks and ordinary saving throws, a 20 or a 1 has no special effect under those rules, though many tables play it differently.

How the rolls are made

Each die comes from crypto.getRandomValues, the random source browsers provide for security work, instead of the faster Math.random. Turning a large random number into a die face with a plain remainder would make some faces very slightly more common, so the roller throws away the rare values that cause that and draws again. The code that reads your notation and keeps or drops dice has automated tests, including advantage ties and exploding dice.

Your history and the sound setting are saved only in this browser. Nothing is sent to us. If your browser blocks storage, the roller still works; it just forgets when you close the page.

Dice roller questions

How do I roll with advantage?

Press "d20 advantage", or type 2d20kh1 (two d20s, keep the highest one). Add your bonus at the end, for example 2d20kh1+5. For disadvantage, use 2d20kl1, which keeps the lowest.

What does 4d6kh3 mean?

Roll four six-sided dice and keep the highest three. It is the usual way to roll ability scores. 4d6dl1 (drop the lowest one) gives the same result.

Is an online dice roller as random as real dice?

This one draws from your browser's cryptographic random number source, the same kind used for security keys, and throws away the few values that would make some faces more likely than others. Each face of each die has the same chance on every roll.

Does the roller work offline?

Yes, once you have opened the page with a signal. Your roll history stays on your device and is never sent anywhere.

Can I use it for D&D?

Yes. It handles the standard fifth edition rolls (advantage, disadvantage, keep or drop dice), and the roleplaying tools page has an initiative tracker, a point buy calculator and an encounter calculator that work alongside it. Starting a new character? The character creator builds one step by step, and the token maker turns its portrait into a round token for your virtual tabletop. It works just as well for board games and any other game that needs dice.