D20 roller
Twenty faces. A 20 is 5 percent.
Roll to draw new faces. Nothing is chosen yet.
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Rolls you make in this visit show up here.
Each tap is a new pseudorandom draw via crypto.getRandomValues. Not atmospheric noise. How the draw works
About this page
A twenty-sided die is the usual way a tabletop check turns into a number. This page rolls one d20, faces 1 through 20, each at 5 percent. A 20 is not more likely because the table is excited, and a 1 is not a moral outcome. The expected value is 10.5. You can add more d20s if you really want several independent twenties. That is not the same as advantage. Advantage would roll twice and keep one, which this preset does not do. The tray is also a sum, not a keep-highest rule. Bring your sheet's math with you. The roller supplies the integer. It does not know your bonus, your difficulty, or the publisher's rulebook.
Related
Questions
What is the chance of a natural 20?
1 in 20, or 5 percent, on one fair d20. The chance of a 1 is the same. The chance of rolling 20 twice in a row on separate checks is 1 in 400. Those figures assume you accept both rolls. Fishing for a 20 by rerolling until it appears is a different experiment, and it ruins the meaning of the probability.
How is a d20 different from two d10s?
A d20 is uniform: every integer from 1 to 20 is equal. Two d10s added together pile up in the middle. A percentile pair is a different construction again. If the rule says d20, roll the d20. If the rule says 2d10, do not 'approximate' it here.
Can I roll more than one d20?
Yes. Raise the dice count. You will see each face and a sum. If your rule is 'roll two and take the higher,' this sum will mislead you. Roll once, note it, roll again, and compare. Or do that comparison by hand from two single rolls. The page will not silently drop the lower die.
Is this an official rules engine?
No. ChanceKit is not affiliated with any game publisher. It does not apply proficiency, difficulty classes, critical hit tables, or advantage. Those are your table's job. Using a digital d20 at a friendly table is fine when everyone can see it. A tournament may want different tools.
Why is a d20 useful in class?
Twenty is a round probability. Five percent is easy to say, and students can tally how often a 20 appears in a hundred rolls. They should expect about five, and they should expect not to hit five exactly. The exercise teaches sample variation better than a lecture that only says '1 in 20.'
Does the page preload a critical hit?
No. Each roll is chosen when you press the button. Animation only reveals that draw. The browser uses crypto.getRandomValues and rejection sampling, which the methodology page spells out. This is not a loaded die, and it is not atmospheric noise. A fresh visit shows no face. Anyone claiming the site 'always rolls high' can watch the history fill in. It will not always roll high.
How do I add a bonus without hiding the die?
Read the d20 first, then add the bonus on paper or switch to the tray and type the modifier. Keeping the raw face visible matters when a rule treats 1 or 20 before bonuses. A summed total alone can hide a natural 20 inside 20 plus 5. This page shows the face. The tray shows faces and then the arithmetic. Neither page decides whether the check succeeded.