D12 roller
Twelve faces, from 1 to 12.
Roll to draw new faces. Nothing is chosen yet.
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Recent rolls
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
Twelve faces are enough for a calendar month, a clock hour, or a tabletop weapon die, and those are three different uses of the same sample space. This page rolls 1 through 12. Each face is 1/12, a little over 8 percent. The expected value is 6.5. A 12 is uncommon relative to a d6's maximum, and it is still a fair face, not a crit unless your rule says so. You can roll more than one d12 and read the sum of independent draws. Mixing a d12 with a d8 belongs on the tray. The result area stays empty until the first roll, including the dash where the total will go.
Related
Questions
What is a d12 good for outside a rulebook?
Months, hours on a 12-hour clock, or any list of twelve that should be equally likely. Number the list first. If the list is names, the wheel is kinder. If the list is 'which month do we use as an example,' a d12 matches the count exactly, including 12.
How rare is a 12?
One in twelve on a single die. Two twelves in a row is 1 in 144. 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. Rarity is not a signal to reroll. Reroll only if the table agreed to a reroll rule before the number appeared.
What is the expected value?
6.5, the midpoint of 1 and 12. The sum of the faces is 78, divided by 12. Students can check that average against a tally. A dozen rolls will wander. A few hundred will sit closer. The page will not force the running mean toward 6.5.
Can the animation land on a different number than the text?
No. There is no second draw hidden in the shake. The numerals in the boxes are the draw. If motion is reduced, the boxes still update. Trust the text if a animation frame ever looks ambiguous.
How do I roll a d12 with other dice?
Open the tabletop tray and set the d12 count beside the other denominations. Keep this page for a pure d12 so the 1-in-12 explanation stays attached to the tool you are using.
Is 1 through 12 on the number tool the same?
For a single draw, yes. Set min 1 and max 12. You lose the die boxes and the easy dice count. You gain a generator that can also do 1 to 100 without pretending it is a die. Use the picture that fits the conversation.
Can I map a d12 onto months or hours?
Yes, if you write the map first: 1 is January or one o'clock, 12 is December or twelve. The roller does not know calendars. A roll of 2 is just 2 until you translate it. Do not reroll February because it feels early in the year. Twelve equal faces is the whole feature. If a month is off limits, remove it from the map and use a smaller range instead of ignoring the face after it appears.