How many unsleeved cards fit in a deck box?

A standard 63x88mm card, the size Magic, Pokemon, One Piece, Disney Lorcana, and Flesh and Blood all use, is 0.305mm thick, so 100 unsleeved cards stack to 30.5mm. A sports card at 0.3mm thick runs 100 cards to about 30mm. A Yu-Gi-Oh, Cardfight Vanguard, or Weiss Schwarz card, the thinner Japanese size at 0.28mm, stacks 100 cards to 28mm. To find how many unsleeved cards fit in a specific box, divide its interior depth by the card's thickness. That gives you the theoretical max. Real deck boxes hold somewhere between 84 and 95 percent of that number once you account for the room cards actually need to sit and shuffle.

The raw math

Card thickness is the whole calculation. No sleeve, no clamshell, no packaging, just the card itself sitting flat against the next one. A standard card at 0.305mm means 10 cards run 3.05mm, 50 cards run about 15.25mm, and 200 cards run 61mm. Sports cards and Japanese-size cards scale the same way, just off a slightly thinner or thicker starting number.

This is the number manufacturers work from when they rate a box for unsleeved capacity, and it's also the number that explains why a box's stated unsleeved rating is always higher than its double-sleeved or single-sleeved rating. Sleeves add bulk on both sides of every card; strip that bulk away and the same interior depth holds a lot more raw cardboard.

Real boxes always fall short of the theoretical max

We pulled every deck box in our data with both a documented interior depth and a stated unsleeved capacity, and compared the stated number against what the raw thickness math says should fit.

Why boxes don't hit the full theoretical number

None of these boxes are cutting it close on purpose to shortchange you. A stack of cards packed to the literal millimeter of a box's interior depth doesn't leave room to riffle through, pull a card out, or close the lid without forcing it, so every manufacturer builds in slack. The sideloading and standard top-loading boxes above land in the low-to-mid 90s for efficiency, close enough that the raw math is a useful estimate on its own. The Vault X Exo-Tec Toploading 80+ sits lower at 84 percent, which tracks with it being a toploading design rather than a sideloader; sliding a stack down into a toploader seems to eat more of the depth in clearance than side-loading a stack in from the edge does.

The exception: big multi-deck storage boxes

The raw depth-divided-by-thickness math only works cleanly on single-stack deck boxes, the kind built to hold one deck standing on its long edge. Larger storage boxes like the Ultimate Guard Superhive 550+ or Arkhive 400+ are wide bins meant to hold many decks side by side, and their listed interior depth doesn't correspond to one continuous card stack the way it does on a Boulder or Sidewinder. If you try to run the same division on those, the numbers won't line up, and that's expected, not an error in the math.

Quick answers

Does sleeve thickness matter for this calculation? Not for unsleeved capacity, by definition. If you're sleeving your cards, you need our guide on how many double-sleeved cards fit instead, since sleeves add real bulk on both sides of each card.

Why is the unsleeved number always so much higher than the double-sleeved number? Because sleeves, especially a double-sleeve combo of an inner and outer, add far more bulk per card than the card itself does. A card is a fraction of a millimeter thick; a sleeved card can run several times that.

Can I just multiply my box's interior depth by 3.28 cards per mm? For a single-stack box holding standard-size cards, that's the right starting point (1 divided by 0.305mm), then knock 5 to 15 percent off for real-world slack based on the numbers above.

The math is simple enough to do on your own for any box once you know its interior depth, and having actual boxes to check the theory against is what turns "should fit about 200 cards" into a number you can trust before you buy.