Know the odds
Probability, made playable.
Expected total7
Chance2.8%
Rolls this session0
D20 roller
Roll a d20, online and free.
A dedicated d20 roller for D&D attack rolls, skill checks, saving throws, and anything else that lives or dies on a twenty-sided die — with advantage, disadvantage, and modifier presets built in.
🔥 0-day streak
ROLL CONFIGURATION1d20
Share a room and everyone sees the same rolls live — no more "did you actually roll that?"
Room
total—
Try 1d20+5, 2d20kh (advantage), or 2d20kl (disadvantage).
Why a dedicated d20 roller
The d20 is the backbone of D&D and most d20-system tabletop games: attack rolls, ability checks, saving throws, and initiative all come down to this one die. Unlike 2d6 or other multi-die pools, a d20 is flat — every result from 1 to 20 has exactly the same 5% chance, so a single roll can swing a scene far more than a bell-curve system would. This page gives that roll its own space: the Advantage and Disadvantage presets roll two d20s and automatically keep the correct one — no mental math, no squinting at two numbers — and a natural 20 or natural 1 is highlighted the instant it lands, so a crit never gets missed at the table.
Want the math behind advantage, disadvantage, and expected value? Read the dice probability guide for a full breakdown, or head back to the main dice roller for 2d6, d100, and fully custom notation.
Frequently asked questions
How do I roll a d20 online?
Use the roller above: it defaults to a single d20. Click "Roll dice", press space, or pick one of the presets for advantage, disadvantage, or a flat modifier.
What does "rolling with advantage" mean?
Advantage means rolling 2d20 and keeping the higher result; disadvantage keeps the lower. Use the "Advantage" or "Disadvantage" preset above (or type 2d20kh / 2d20kl) — both automatically roll two d20s and resolve the correct result for you, dimming the discarded die rather than hiding it.
What are the odds on a d20?
A fair d20 gives every result from 1 to 20 an equal 5% chance — there is no bell curve like there is with 2d6. See the probability panel above for the live odds on your current roll, or read the full dice probability guide for the math.
Can I add a modifier to a d20 roll?
Yes. Type notation like 1d20+5 into the field to roll a d20 and add 5 to the result, matching how attack and skill checks work in most d20-based tabletop games. Modifiers stack with advantage too — try 2d20kh+5.
What happens on a natural 20 or natural 1?
The roller flags it automatically: a natural 20 rings the die in green and shows "Critical hit!" under the total, while a natural 1 rings it in red with "Critical miss!" — matching how most d20 games treat those rolls as automatic hits or misses.