A: BoardGameGeek has an extensive listing of card sizes for a dizzying number of games. If you go to the bottom of the header, just below the alphabet, and click on the little number indicating how many games are listed, it will give you a drop-down where you can scroll through them alphabetically by name all in one list. Be patient after you click; it’s a long list to generate. “Find” also works within that drop-down, which is nice.
Most of our card games have the same size cards, a slightly narrower type many would call “bridge sized” though that’s not a precise category. The card size (roughly, using a ruler) is 87.5 mm tall by 57 mm wide. (Links below go to the BGG sleeve listing for each game, where available. Where not available, keep in mind all of these games’ cards are very similar in size.)
This is for Fluxx, 2nd edition Aquarius (note there’s only one BGG listing for both editions, so make sure you’re looking at the right one), Chrononauts, Just Desserts, Loonacy (oddly this is Mary Engelbreit Loonacy, because the original isn’t in there, but they all have the same size cards), Time Breaker, Are You The Traitor, Are You a Werewolf. The first printing of Just Desserts (and the expansion packs) were slightly off from this, unfortunately. I could swear Choose One cards are just a hair wider on the short side, but they’re VERY close.
Seven Dragons, old Aquarius, and old Nanofictionary are 88.5 mm tall by 63 mm wide. Current Nano and Aquarius are the same size as Fluxx etc.
Get The MacGuffin cards are: 2.87″ x 4.5″
New standalone Zendo box-set cards are the same size as the Pyramid Arcade deck, which is aaaalllmmost the same size as Seven Dragons cards. But not quite. Note that some of the promo cards for additional pyramid games are not quite the same size. Since these cards are just references, we deemed this an annoying, but not game-stopping issue.
See also: What size are the cards in Pyramid Arcade?
For Tiny Fluxx, you might try the sleeve size listed for the Twin Win cards in Pyramid Arcade (see link above).
If we’ve missed a game card size you’re looking for email us at QA@looneylabs.com
If you FIND said missing game on the BGG list, also please email us, and give us the link, and we’ll add it.