D12 Dice Roller

The loneliest die in the bag

Ask any group of role-players which die they roll least and most will say the d12. A standard seven-dice set has one, and in plenty of campaigns it sits in the bottom of the bag for weeks. That’s a bit of a shame, because it’s one of the prettiest shapes in the set: a dodecahedron with twelve pentagonal faces, one of the five Platonic solids.

It does have a devoted fan base, though. Barbarian players.

Who actually rolls a d12

In fifth edition Dungeons & Dragons, the d12 has a handful of important jobs:

• The barbarian’s Hit Die. Barbarians gain 1d12 hit points per level (or a fixed 7), the most of any class. The d12 is basically the barbarian’s personal die.
• The greataxe. 1d12 slashing damage, the classic barbarian weapon.
• The lance. 1d12 piercing, mostly seen on mounted characters.
• Some spells and monsters. A few big hits use d12s, and several monsters’ bite and slam attacks do too.

That’s a short list compared with the d6 or d8, which explains the bag-bottom problem.

Greataxe versus greatsword, settled with numbers

The most common d12 argument at a table is weapon choice: the greataxe (1d12) against the greatsword (2d6). Both are two-handed, both are heavy, and the averages are close. But they feel very different, and the tables show why.

Totals for 2d6 (greatsword) for comparison

Total	Ways	Chance	This or higher
2	1	2.78%	100.00%
3	2	5.56%	97.22%
4	3	8.33%	91.67%
5	4	11.11%	83.33%
6	5	13.89%	72.22%
7	6	16.67%	58.33%
8	5	13.89%	41.67%
9	4	11.11%	27.78%
10	3	8.33%	16.67%
11	2	5.56%	8.33%
12	1	2.78%	2.78%

Probabilities for one d12

Roll	Chance of exactly this	Chance of this or higher
1	8.33%	100%
2	8.33%	91.7%
3	8.33%	83.3%
4	8.33%	75%
5	8.33%	66.7%
6	8.33%	58.3%
7	8.33%	50%
8	8.33%	41.7%
9	8.33%	33.3%
10	8.33%	25%
11	8.33%	16.7%
12	8.33%	8.33%

Put side by side:

Measure	Greataxe (1d12)	Greatsword (2d6)
Average	6.5	7
Chance of 10 or more	25%	16.7%
Chance of 3 or less	25%	8.3%
Chance of exactly the maximum	8.3%	2.8%
Most likely result	All equal	7

So the greatsword is steadier and slightly stronger on average, while the greataxe is streakier. A barbarian with Brutal Critical (in the 2014 rules) adds extra weapon dice on a crit, and a single big die benefits from that more, which is a big part of why barbarian players stay loyal to the axe. The other part is that it’s an axe.

The odds on twelve faces

Each face is one in twelve, about 8.3%. The average is 6.5. Because the d12 is the flattest common die after the d20, rolls feel dramatic: an 11 or 12 comes up one roll in six.

Twelve as a calendar die

Outside games, twelve maps onto so much of daily life that a d12 doubles as a calendar tool:

1. A random month. 1 is January, 12 is December. Handy for “birthday month” party games.
2. A random hour. For analogue clock practice with young kids.
3. A zodiac sign. Our zodiac sign wheel has them labelled if you’d rather spin.
4. A times table. Roll two d12s and multiply for a random fact up to 12 × 12.

Rolling a d12 when you don’t own one

There’s a neat trick for making a d12 from more common dice: roll a d6 and toss a coin. Heads, add 6 to the d6; tails, use the d6 as it is. That gives every number from 1 to 12 equally. What you can’t do is roll 2d6 and call it a d12, because 2d6 can’t roll 1 and loves 7.

Or, of course, roll it here.

Ancient twelve-sided mysteries

A fun fact for history-minded players: archaeologists have found more than a hundred small hollow bronze dodecahedra across the former Roman Empire, mostly from the second to fourth centuries. Each face has a round hole, and the holes come in different sizes. Nobody knows for sure what they were for. Theories range from surveying tools to knitting aids to religious objects. They’re almost certainly not dice, but they’re the most famous twelve-sided objects in archaeology, and they look very at home next to a modern d12.

For more dice, the d20 roller is next door, and the 1 to 12 number page has more calendar-flavoured ideas.

Barbarian hit points: roll or take 7?

At each level, a barbarian can roll 1d12 for extra hit points or take the fixed value of 7. Rolling beats 7 on an 8 through 12: five faces out of twelve, about 42%. It ties on a 7 and loses on 1 to 6, half the time. The rolled average is 6.5, so over a full career of 19 level-ups, rolling instead of taking the fixed value costs about 9.5 hit points on average.

That doesn’t sound like much, but the spread is the real risk. Roll badly across a few levels and a front-line character can end up noticeably fragile. Many tables let players roll and then take the fixed value if the roll comes out lower, which removes the downside entirely. If your group plays that way, rolling is pure upside, and you’ll average a little over 8 per level.

Picking things in dozens

Any time something comes in twelves, a d12 can choose from it: a dozen eggs in a cookery lesson (which one gets cracked for the demonstration), twelve jurors in a mock trial, a dozen songs on a playlist. And for a deck of card prompts that’s been cut down to twelve, the d12 picks the card faster than shuffling.

Twelve faces, little clutter

One practical point in the d12’s favour: its faces are big. Each pentagon has plenty of room for a clearly printed number, so physical d12s are among the easiest dice to read across a table. They also roll well, settling faster than a d20 but tumbling more than a d6. If you ever buy a single fancy die as a gift for a role-player, a metal or gemstone d12 is a quietly great choice, mostly because they never seem to own a nice one.

On screen, of course, readability isn’t an issue. The roller shows each result as a plain number, and with Dice set above one it lists every d12 along with the total, so a big greataxe crit with extra dice is easy to add up and double-check.