Gaming · Dice
Advantage and disadvantage dice odds calculator.
Roll any dice expression twice and keep the higher or lower total. See the exact chance of hitting a number and the average each way.
The roll
Result
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What this calculator does
Advantage in fifth edition means rolling a second d20 and using the higher; disadvantage means using the lower. The d20 case has a simple answer, and a separate calculator on this site covers it with an attack roll's natural 1 and 20 rules. People also ask about other dice: what does advantage do to 2d6, a d12 or a d100? The same rule, take the best of two rolls, has an exact answer, and this page computes it for any dice total.
The d20 rules in the SRD apply advantage to d20 tests only. Using it on damage dice or on a custom system's roll is a house rule or a different game's rule, and this tool treats it as exactly that: roll the whole expression twice and keep the higher or lower total. The result is a full set of chances and averages you can check against your own table.
Worked example
For 2d6 against a total of 10, one roll reaches 10 or more with probability 16.7% (6 of 36 outcomes). With advantage, you fail only if both rolls fall short: 1 - (30/36)^2 = 30.6%. With disadvantage both must succeed: (6/36)^2 = 2.8%. The average total moves from 7 to 8.37 with advantage and 5.63 with disadvantage. As a check, a plain d20 needing 11 gives 50%, 75% and 25%, and the average of advantage is 13.825 against 7.175 for disadvantage. Rolling three d20 and keeping the best raises that 50% target to 87.5%.
How it is calculated
The distribution of the dice total is built exactly by convolution, so there is no simulation noise. For a target t (after the modifier), let p be the chance a single roll reaches t. Keeping the best of k rolls reaches t unless all k miss: 1 - (1 - p)^k. Keeping the worst needs all k to reach it: p^k. Average totals use the cumulative distribution F: the best of k has mean the sum of x times (F(x)^k - F(x-1)^k), and the worst of k has mean the sum of x times ((1-F(x-1))^k - (1-F(x))^k). The table at the bottom repeats the chance for each total in range.
The "Advantage and Disadvantage" rules in the Using Ability Scores section of SRD 5.1. Odds for dice other than the d20 are mathematics, not published rules. Last checked 2026-10-26.
What this does not cover
- Attack-roll rules such as a natural 20 always hitting are not applied. For a single d20 attack use the d20 calculator linked below.
- Advantage on dice other than a d20 is not a 5e rule; the tool just applies the same take-best idea.
- Rolls with rerolls, exploding dice or keep-highest within one roll are not covered. The 4d6 drop lowest page handles keep-highest.
- Cancelling advantage and disadvantage is a rules question: the SRD says they cancel, and you roll one die.
Common mix-ups
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Often assumedAdvantage is the same as a flat bonus of about +5.
What the source saysThe SRD says advantage means rolling a second d20 and using the higher roll. It adds no flat bonus, and its effect on your chance depends on the number you need. [1]
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Often assumedTwo sources of advantage let you roll three dice.
What the source saysThe SRD says that if multiple situations grant advantage you still roll only one additional d20. [1]
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Often assumedWith two sources of disadvantage and one of advantage you still have disadvantage.
What the source saysThe SRD says that if a roll has both advantage and disadvantage you are considered to have neither, and this is true even if multiple circumstances impose disadvantage and only one grants advantage. [1]
Checked against these sources on .
Frequently asked questions
What is the average of 2d6 with advantage?
8.37, against 7 for a normal 2d6 roll. Advantage on the whole expression means roll 2d6 twice and keep the higher total.
How much does advantage raise the odds on a d20?
For a 50% target it raises the chance to 75%, and disadvantage lowers it to 25%. The gain is biggest near the middle of the range and shrinks as the target gets very easy or very hard.
Do advantage and disadvantage cancel out?
Yes. The SRD says if a roll has both advantage and disadvantage you have neither and roll one d20, even if several circumstances impose disadvantage and only one grants advantage.
Can you get advantage twice?
No. The SRD says if multiple situations grant advantage you still roll only one additional d20. The three-roll option here is for features that explicitly add a third die.
Is advantage the same as a +5 bonus?
No. On a d20 it adds 3.325 to the average (13.825 against 10.5) and is worth more when you need a middling number and less at the extremes. A +5 bonus always adds exactly 5.
Sources
Checked
The "Advantage and Disadvantage" rules in the Using Ability Scores section of SRD 5.1. Odds for dice other than the d20 are mathematics, not published rules. Runs entirely in your browser. Nothing you type is sent or stored.
Disclaimer
TNAADO is not affiliated with Wizards of the Coast. This tool is compatible with fifth edition and uses game names only to describe what it is for. Odds and totals are arithmetic from the cited rules, and your table's house rules may differ. This work includes material taken from the System Reference Document 5.1 ("SRD 5.1") by Wizards of the Coast LLC and available at https://dnd.wizards.com/resources/systems-reference-document. The SRD 5.1 is licensed under the Creative Commons Attribution 4.0 International License available at https://creativecommons.org/licenses/by/4.0/legalcode.