A twenty-sided die without the die
Tabletop role-playing games lean on the twenty-sided die, usually written d20, for the roll that decides whether a swing connects, a lock gives way or a bluff holds. Dice get lost, left at the other player's house, or become awkward when the group plays over video. This page is a plain 1 to 20 draw. Press, read the number, add your modifier.
It is not tied to any game or publisher, so any rule set that asks for a twenty-sided roll works the same way. Many systems treat a 20 or a 1 as special, and that is up to your rulebook. Some rule sets let you roll twice and keep the better result. Set Count to 2 with Allow repeats on and take the higher number. Two rolls give you at least one 20 about 9.75 percent of the time, against 5 percent for a single roll.
Under the button, twenty values need five random bits, which gives 32 candidates. The 12 that fall past 20 are discarded and redrawn, so 37.5 percent of raw draws never reach you, and the other twenty stay exactly level. The methodology page has the full explanation.
Picking from a class of twenty
Twenty is a common class size, and it maps neatly onto a numbered roll. Write the numbers beside the names, press once, and the matching student answers the next question. Nobody has to wonder whether the teacher was picking favorites.
For several students at once, set Count to 5 and untick Allow repeats. You get five different numbers, and each student has a 25 percent chance of being among them (5 out of 20). The page does not remember earlier draws. If you want nobody repeated across a week, cross names off the list yourself.
Splitting the same twenty into groups is a different job, and the team generator is built for it. Give it the names and it does the whole split in one pass.
Guessing games and what 1 in 20 means
Hidden-number games. The host presses and keeps the screen to themselves. A single blind guess wins 5 percent of the time. Add "higher" or "lower" hints and five guesses are always enough, because each answer cuts the field roughly in half. Four guesses are not always enough, which is handy for settling an argument.
Droughts are normal. A specific number missing for twenty presses in a row happens about 36 percent of the time, and the same number appearing at least once in those twenty presses happens about 64 percent of the time. If your lucky 17 has not shown up, it is not hiding.
Neighboring ranges: the 1 to 6 page works as an ordinary die, 1 to 10 is the classic guessing span, and 1 to 100 handles percent-style rolls. For a yes-or-no decision, the coin flip is simpler than any number.
All randomization on Spinness uses crypto.getRandomValues() — the browser's cryptographic random source. Learn how our randomness works.
Frequently asked questions
Can I use this as a d20?
Yes. It returns a whole number from 1 to 20, both ends included, with every value at 5 percent, which is what a fair twenty-sided die gives. Add your modifiers to the number as you normally would.
How do I roll twice and keep the higher result?
Set Count to 2, leave Allow repeats ticked and press once. You see two independent numbers and take the higher one yourself.
How do I pick several students without choosing anyone twice?
Set Count to the number of students you need and untick Allow repeats. One press returns that many different numbers. Match them to your class list and you are done.
What are the odds of getting one specific number?
Exactly 1 in 20 per press, which is 5 percent. Over twenty presses, that number shows up at least once about 64 percent of the time, so a miss is common and says nothing about fairness.
Are 1 and 20 less likely than the middle numbers?
No. The draw is flat across all twenty values. Adding up several dice behaves differently, because totals near the middle turn up more often than the extremes. Here the edges are exactly as likely as anything else.
Is my result stored or sent anywhere?
The draw is calculated in your browser and the number stays on your screen. Closing the tab or pressing again replaces it, and nothing in the draw needs a server.