Every face has a 1 in 4 chance — 25% each. Average roll: 2.5.
The d4 is the smallest die in the polyhedral set and the strangest one to read. A tetrahedron has no face pointing up when it lands, so instead of reading the top you read the numbers along the bottom edges or at the upward point, depending on how the die was engraved.
It is the die of small, frequent numbers: dagger damage, a Bless bonus, the extra point on a Magic Missile dart. Rolling it here skips the part where it skitters off the table and lands wedged against a book.
There are two engraving conventions and they are read in opposite directions. On an apex-read d4, each of the three visible corners shows a number at the top point, and all three read the same — that is your result. On a base-read d4 (sometimes called Crystal or pyramid style), the numbers sit along the bottom edge of each face and you read the one on the face turned toward you, which will also be the number resting flat against the table.
If you own both kinds it is worth checking before a session, because a die where 1 sits at the apex and 4 at the base can be read two ways by two players and start an argument that lasts longer than the fight.
A tetrahedron has the fewest faces and the bluntest tumble of anything in the set. Where a d20 keeps turning over for a second or two, a d4 tends to land, tip once, and stop — which is why players fling them, and why they end up on the floor. The sharp vertex is also the reason for the nickname "caltrop", after the four-spiked object designed to always land point-up. Anyone who has stepped on one barefoot at 1am understands the comparison.
None of that affects fairness on a well-made die, but it does mean a d4 is unusually sensitive to being dropped rather than rolled. A short drop onto a hard surface is not really a randomising event.
A common instinct is that 2d4 and 1d8 are interchangeable because both top out around eight. They are not. 1d8 gives every result from 1 to 8 an equal 12.5% chance and averages 4.5. 2d4 runs from 2 to 8, averages 5, and clusters hard in the middle — a 5 comes up 25% of the time while an 8 comes up 6.25%.
So 2d4 is slightly better on average, much more predictable, and can never roll a 1. That trade matters when you are choosing between a weapon and a spell that look similar on paper.
A d4 has no upward face. On apex-read dice, all three visible corners show the same number at the top point — that is the result. On base-read dice, you read the number along the bottom edge of the face turned toward you. Check which kind you have before someone reads it the other way.
Because a tetrahedron, like the four-spiked caltrop it is named after, always lands with a point sticking up. It is a joke about stepping on one in the dark, and it is also why the d4 is the die most likely to be found under the sofa.
They are different rather than strictly better. 2d4 averages 5 to the d8’s 4.5 and cannot roll below 2, but it clusters around the middle instead of spreading evenly. Take 2d4 if you want consistency, 1d8 if you want the chance of a bad roll balanced by the chance of a great one.
Seven dice come in the set and new players are told to buy them before anyone explains what they do. This is what each one is for.
The maths behind why some rolls feel reliable and others feel like coin flips — with the numbers you can actually use at the table.
Every rulebook writes rolls in the same compact shorthand. Here is how to read it, including the keep and drop notation that trips people up.
Last updated: August 20, 2026
