Roll a d20

A d20 is a twenty-sided die and the most important die in D&D. Each number from 1 to 20 has an equal 5% (1 in 20) chance, and the average roll is 10.5. You roll a d20 for every attack roll, saving throw and ability check, then add your modifier. Press Roll below to roll one instantly.

Bonus

d20 3D dice Dice colour

d20 odds and average

Minimum 1, maximum 20, average 10.5. Every face has a 5% chance on a fair die.

Roll	Chance of exactly this	Chance of this or higher
1	5%	100%
2	5%	95%
3	5%	90%
4	5%	85%
5	5%	80%
6	5%	75%
7	5%	70%
8	5%	65%
9	5%	60%
10	5%	55%
11	5%	50%
12	5%	45%
13	5%	40%
14	5%	35%
15	5%	30%
16	5%	25%
17	5%	20%
18	5%	15%
19	5%	10%
20	5%	5%

Where you roll a d20 in D&D

Attack rolls: Roll a d20, add your ability modifier and proficiency bonus, and compare the total to the target's Armor Class. A natural 20 always hits and is a critical hit; a natural 1 always misses. See the odds of rolling a natural 20.

Saving throws and ability checks: Roll a d20, add the relevant modifier, and try to meet or beat a Difficulty Class set by the DM or the spell. The 2024 rules group attack rolls, saving throws and ability checks together as "D20 Tests". Read more about saving throws and skill checks.

Advantage and disadvantage: Roll two d20s and keep the higher (advantage) or lower (disadvantage). Select the d20 twice above, or type 2d20kh1 into the dice calculator. Advantage raises the average roll from 10.5 to 13.825; see how advantage changes your odds.

Initiative and death saves: Initiative is a Dexterity check rolled on a d20 at the start of combat, and a creature at 0 hit points rolls a d20 death saving throw each turn, succeeding on a 10 or higher.

Roll a d20 FAQ

What is the average roll on a d20?

The average roll on a d20 is 10.5, because the numbers 1 to 20 add up to 210 and 210 / 20 = 10.5. With advantage the average rises to 13.825, and with disadvantage it falls to 7.175.

What are the odds of rolling a 20 on a d20?

Exactly 5%, or 1 in 20. With advantage the chance of at least one 20 rises to 9.75%, and with disadvantage it drops to 0.25%.

What does a natural 1 do in D&D?

On an attack roll, a natural 1 always misses. In the core rules a natural 1 is not an automatic failure on ability checks or saving throws, although many tables play it that way. Death saving throws are the exception: a natural 1 counts as two failures.

How do I roll a d20 with advantage here?

Click the d20 twice so two are selected, press Roll and keep the higher number. Or type 2d20kh1 into the dice calculator, which keeps the highest die for you.

Is "roll 1d20" the same as "roll a d20"?

Yes. The 1 in 1d20 means one die. Dice notation puts the number of dice before the d and the number of sides after it, so 2d20 means two twenty-sided dice.

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About this roller

DnD Dice Roller (dnddiceroller.org) rolls every die with your browser's cryptographically secure random number generator, crypto.getRandomValues, and uses rejection sampling so every face is exactly equally likely. The 3D dice only animate a result that has already been decided this way; the physics never picks the number. Rolls happen on your device and are never sent to our server.

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Contains content from the System Reference Document 5.1 and 5.2 by Wizards of the Coast LLC, used under the Creative Commons Attribution 4.0 International License.