Roll 2d20

Rolling 2d20 means rolling two twenty-sided dice. In D&D 5e you almost never add them: you keep the higher die for advantage or the lower die for disadvantage. Advantage raises the average from 10.5 to 13.83 and the chance of a natural 20 from 5% to 9.75%. Added together, 2d20 totals 2 to 40, averaging 21.

Bonus

d20 3D dice Dice colour

2d20 added together

2d20 ranges from 2 to 40, averages 21, and is most likely to total 21.

Total	Chance	This or higher
2	0.25%	100%
3	0.5%	99.75%
4	0.75%	99.25%
5	1%	98.5%
6	1.25%	97.5%
7	1.5%	96.25%
8	1.75%	94.75%
9	2%	93%
10	2.25%	91%
11	2.5%	88.75%
12	2.75%	86.25%
13	3%	83.5%
14	3.25%	80.5%
15	3.5%	77.25%
16	3.75%	73.75%
17	4%	70%
18	4.25%	66%
19	4.5%	61.75%
20	4.75%	57.25%
21	5%	52.5%
22	4.75%	47.5%
23	4.5%	42.75%
24	4.25%	38.25%
25	4%	34%
26	3.75%	30%
27	3.5%	26.25%
28	3.25%	22.75%
29	3%	19.5%
30	2.75%	16.5%
31	2.5%	13.75%
32	2.25%	11.25%
33	2%	9%
34	1.75%	7%
35	1.5%	5.25%
36	1.25%	3.75%
37	1%	2.5%
38	0.75%	1.5%
39	0.5%	0.75%
40	0.25%	0.25%

How 2d20 works in D&D 5e

Advantage: When something gives you advantage on an attack roll, ability check or saving throw, roll two d20s and use the higher one. It is worth roughly +3 to +5 on a typical roll. If you need an 11, your chance goes from 50% to 75%. If you need a 15, it goes from 30% to 51%. Common sources are attacking a creature that can't see you, an ally taking the Help action, and monster traits like the dire wolf's Pack Tactics. Press Roll with both d20s and keep the higher, or type 2d20kh1 into the notation box under the roller and it keeps the higher die for you. Full odds are in advantage and disadvantage in 5e.

Disadvantage: Roll two d20s and use the lower one. This hurts more than people expect. Needing an 11 drops from 50% to 25%, and needing a 15 drops from 30% to just 9%. A natural 20 with disadvantage only happens 0.25% of the time (both dice must show 20), while a natural 1 jumps to 9.75%. Type 2d20kl1 to have the roller keep the lower die. Advantage and disadvantage never stack: three sources of advantage still means two dice, and if you have both at once they cancel and you roll a single d20.

Inspiration, 2014 vs 2024: In the 2014 rules, spending Inspiration gives you advantage on one attack roll, saving throw or ability check, so it is a 2d20 roll. In the 2024 rules, Heroic Inspiration works differently: you reroll one die after seeing it and must use the new result. Rerolling a bad d20 is similar to advantage but not the same, since you decide after the first roll. If you actually add 2d20 together, the totals form a triangle from 2 to 40 with 21 the most likely result at 5%. See inspiration in 5e for the details.

Roll 2d20 FAQ

Do you add the two d20s together for advantage?

No. With advantage you keep the higher of the two d20s, and with disadvantage you keep the lower. You only add 2d20 together if a specific game tells you to.

What is the average roll with advantage?

The average of the higher of two d20s is 13.825, compared with 10.5 for one d20. With disadvantage the average drops to 7.175.

What are the odds of a natural 20 with advantage?

With advantage the chance that at least one die shows 20 is 9.75% (39 in 400). With disadvantage you need both dice to show 20, which is 0.25% (1 in 400).

Do multiple sources of advantage stack?

No. However many sources you have, you roll only two d20s. If you have at least one source of advantage and one of disadvantage, they cancel and you roll one d20.

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About this roller

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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.