The short version: Take a standard deck of playing cards, remove the kings and jokers, and you’re left with 48 cards. Treat aces as 1, jacks as 11 and queens as 12. You can now simulate every standard D&D polyhedral die using these rules:

Die	How to roll
d2	Draw a card. Red is heads, black is tails.
d4	Draw a card. Repeatedly subtract 4 until the result is 1–4.
d6	Draw a card. Repeatedly subtract 6 until the result is 1–6.
d8	Draw a card. Repeatedly subtract 8 until the result is 1–8.
d10	Draw a card. Redraw jacks and queens.
d12	Draw a card. Use its value directly.
d20	Draw a card, redrawing jacks and queens. Add 10 if the card is red.

For independent rolls, return the card to the deck and reshuffle each time.

Why bother?

I’ve been playing All Night Breakfast at the Midnight Owl, a solo tabletop roleplaying game that uses both a standard deck of playing cards and all the D&D polyhedral dice.

I’ve been enjoying it, but did’t want to carry both the dice and the deck. Part of the appeal of a solo game is being able to take it somewhere, sit down with a notebook and play. Having to bring a separate set of dice isn’t a huge inconvenience, but it would be nice to get rid of the extra encumbrance.

Hopefully, this is a useful little technique. I’m sure it’s not new…

Drop the Kings and Jokers and go to 48 cards

Decks have 13 cards of four suits, and two jokers. Ignore the Kings and Jokers, and you’ve got 48 cards – evenly divisible by 2, 4, 6, 8 and 12. In other words, all the usual polyhedral dice except the d10 and d20.

Treat aces as 1, number cards as their face values, jacks as 11 and queens as 12.

To roll a d2, d4, d6 or d8, draw a card. If its value is greater than the number of sides on the die, keep subtracting the number of sides until you get a result in the right range.

For example, to roll a d4:

• Draw a 3 and you’ve rolled 3.
• Draw a 6, subtract 4, and you’ve rolled 2.
• Draw a jack (11), subtract 4 twice, and you’ve rolled 3.
• Draw a queen (12), subtract 4 twice, and you’ve rolled 4.

For a d12, simply use the card’s value directly.

Because the deck contains exactly 48 cards, each possible result occurs equally often for a d2, d4, d6, d8 or d12.

What about the d10 and d20?

These need slightly different tricks, but they’re still easy.

For a d10, draw a card, treating aces as 1 and number cards as their face values. If you draw a jack or queen, redraw.

For a d20, do exactly the same thing, but look at the card’s colour:

• Black card: use the value as it is, giving a result from 1 to 10.
• Red card: add 10, giving a result from 11 to 20.

So a black 7 is a 7, while a red 7 is a 17.

Each possible result is equally likely, provided you’re drawing from a properly shuffled deck.

Draw a Card? Cut a Card? Shuffle?

Drawing cards isn’t quite the same as rolling dice, because cards are removed from the deck as you use them. That means successive results aren’t independent, and the probabilities change as cards are drawn.

If you want to reproduce ordinary dice rolls exactly, you should return each card to the deck and reshuffle before the next draw. Being a bit lazy – or if you prefer less ‘swingy’ results – draw several cards before reshuffling, accepting that the results won’t be quite the same as independent dice rolls.

Personally, I’m cutting the deck, placing the top half on the bottom, then reading the bottom card. It’s nearly as good as replace-and-reshuffle, and it’s definitely good enough for my needs, which is to cause a little narrative chaos, not simulate a fair random number generator.

One less thing to carry

So that’s it. One ordinary deck of cards, four kings removed or ignored, and you’ve got a way to simulate the whole standard set of D&D polyhedral dice.

It’s not a revolutionary discovery, and I’m sure other people have done similar.

And now I can sit down with All Night Breakfast at the Midnight Owl, a notebook and a deck of cards, without needing to remember the dice as well.

No jokers, no kings, no extra encumbrance!