Pokémon card size, sleeves and storing cards in a humid climate

A Pokémon card is 63.5 × 88.9 mm (2.5 × 3.5 inches) — the size the industry calls "standard" — and that is true of Japanese Pokémon cards as well as English ones. If you have ever bought "Japanese size" sleeves for Japanese Pokémon cards and found them wrong, that is why: the label refers to a different card format, not to the Japanese language. Get that sorted, then deal with the thing that actually damages cards in Malaysia, which is humidity.

The sizes, and the sleeve label that misleads everyone

Source: Safely Sleeved's sleeve-size guide, which states plainly that "Pokémon cards are standard size regardless of the language they were printed in, so the same sleeves fit English and Japanese cards alike." Ultra Pro's officially licensed Pokémon sleeves agree — they are "sized for standard size trading cards measuring 2.5 in. x 3.5 in." with no language qualifier.

So: buy standard sleeves for every Pokémon card you own, English or Japanese. The "Japanese size" category exists for Yu-Gi-Oh! and Cardfight!! Vanguard, which really are smaller. Putting a standard Pokémon card in a small sleeve doesn't work, and putting it in a sleeve meant for a smaller card leaves it loose enough to slide and rub — which is how edge wear starts.

If you double-sleeve, the inner sleeve goes on snugly and the outer sleeve is the larger one. Both are standard-category for Pokémon.

Humidity is the real enemy here

Malaysia's climate is the part of card storage that overseas guides simply don't address. MET Malaysia lists consistently high humidity as a defining feature of the country's climate — which anyone who has lived here does not need to be told.

I want to be careful about how strongly I put the next part. I am describing what we see on cards that come in after years in a cupboard, and the mechanisms are well understood in paper conservation generally, but I have not run a controlled study on Malaysian storage conditions and I'm not going to pretend otherwise. Treat it as informed practice, not as measured data:

• Warping. Cardstock absorbs moisture unevenly and the card develops a bow. A warped card can still grade, but warping frequently comes with surface and corner problems that don't.
• Sleeve sticking. In sustained humidity a card can begin to adhere to the inside of a sleeve. Pulling it free is how people tear the surface layer of an otherwise clean card.
• Foil separation. Holo and full-art cards have layers. Moisture cycling works at those layers, and the result shows up as clouding or lifting along the foil.

None of this is dramatic and none of it happens overnight. It is slow, cumulative, and completely preventable.

What actually helps

• Store cards indoors, in the air-conditioned part of the house. Air conditioning dehumidifies as a side effect. A room that stays closed and unconditioned is the worst place in a Malaysian home for cards.
• Use an airtight box with silica gel, and replace or recharge the gel — spent silica does nothing. This is the single cheapest meaningful improvement most collectors can make.
• Keep cards off exterior walls and away from windows, where condensation and temperature swings concentrate.
• Don't stack heavy things on flat-stored cards. Pressure plus humidity is how you get a permanent bow.
• Never store cards in a car. A parked car in Malaysian sun is a heat chamber, and heat plus trapped moisture will warp a card in a single afternoon.

If you're sending a card for grading

This is where the sleeve choice stops being about storage and becomes a requirement. Our own packing guide asks for a penny sleeve, then a semi-rigid holder — a Card Saver I or II — and specifically not a top loader, because a top loader lets the card move around in transit.

That isn't a MAG quirk — it's the industry norm. Dave & Adam's, which runs a PSA submission centre in Europe, publishes the same requirement in stronger terms: semi-rigid holders such as Card Saver I for all submissions, with top loaders and screw-down holders "strictly prohibited, as they cause significant processing delays," and a 5% processing and handling charge on its own orders that arrive packed incorrectly (Dave & Adam's PSA shipping guide). That 5% is that centre's policy, not a universal PSA fee — but the packing requirement itself is standard across graders, and it exists for a practical reason: a semi-rigid holder lets a grader remove the card quickly without flexing it, and a rigid top loader does not.

Use clear penny sleeves, too. Opaque or coloured ones mean the card has to be taken out to be seen, which is handling nobody wants.

So the order is: clear penny sleeve → semi-rigid holder → protected in the parcel. Not a top loader, not a screw-down. If you're submitting an unusually thick card and think it needs something else, ask us first rather than guessing.

One more thing worth saying plainly, because it's the mistake that costs people the most: don't clean the card. Wiping a surface to remove a mark is how a light scuff becomes a permanent scratch, and it is not recoverable. Whatever is on the card, leave it. If you want to think through whether a card is worth submitting at all, our pre-grade self-check walks through centering, corners, edges and surface — it's a practical checklist, not a scoring tool, and it won't tell you what grade you'll get.

The short version

Every Pokémon card is standard size — 63.5 × 88.9 mm — whatever language it's printed in, so buy standard sleeves and ignore the "Japanese size" label, which is for Yu-Gi-Oh!. Then treat humidity as the main threat, because here it is: conditioned air, an airtight box, live silica gel, and nothing heavy on top. When a card is going out for grading, penny sleeve and a Card Saver — never a top loader.

If you want to see how the four subgrades are actually assessed before you decide anything, that's on our grading standards page.