Advantage and Disadvantage Roller

This free advantage roller is for D&D 5e players and game masters who need to roll two d20s and keep the higher or the lower die. It starts in advantage mode. Switch to disadvantage or a normal d20, add your modifier, and set a DC or AC to see your chance before you roll.

How to use the advantage roller

Tap to roll. Press the big die. Advantage rolls two d20s and keeps the higher face. Disadvantage keeps the lower face. A normal roll uses one d20. Both faces stay visible so the table can see which die counted.

Add a modifier and a target. Type the bonus you use at the table, then a DC or Armor Class. The chance shown is the chance that your kept die plus the modifier meets or beats that number, before any natural 20 or natural 1 rule on an attack roll.

Need typed notation such as 2d20kh1+5, or a mix of other dice? Use the main DnD dice roller. For a general twenty sided page with the same modes, open the d20 roller.

How advantage and disadvantage work

Advantage means you roll a second d20 and use the higher result. Disadvantage means you use the lower result. Your ability modifier and other bonuses are added once, after you pick the die that counts. The advantage roller starts in advantage mode and can switch to disadvantage or a normal d20.

Those two states apply to the core d20 rolls: attack rolls, ability checks and saving throws. They do not change damage dice. After you hit, roll weapon or spell damage on the matching die page or on the main roller.

When they cancel, and when they do not stack

If you have both advantage and disadvantage on the same roll, they cancel and you roll one d20. It does not matter how many reasons you have for each side. One source of each is enough to cancel.

Two sources of advantage still mean two dice, not three. The same is true of disadvantage. The extra source is useful only if something later would have cancelled the first one.

How much advantage helps

The shift is largest when you need a middling number. If you need 11 or higher, one d20 succeeds 50% of the time, advantage raises that to 75%, and disadvantage drops it to 25%. We counted all 400 ways two d20s can land to get these figures:

The average face on one d20 is 10.5. With advantage it is 13.825, and with disadvantage it is 7.175. For any other target, use the dice probability calculator.

Related combat tools

If a feature gives you advantage on initiative, roll it here or on the d20 page, then type the kept total into the initiative tracker. A natural 20 or a natural 1 on a death saving throw is still a plain d20: mark those on the death saves tracker. Ability saves against a DC belong on the saving throw roller, and to-hit rolls against Armor Class belong on the attack roller.

Each roll uses your browser's cryptographic random number generator, with extra values thrown out so no face is favored. See the about page for the method.

Advantage roller FAQ

See the Nat20 Roller FAQ for more on notation, advantage and how rolls stay random.