MTG card sleeves

Size: standard, and nothing else

A Magic card measures 63.5 × 88.9 mm. That is the same 2½ × 3½ inch card used by Pokémon, Lorcana, One Piece, Flesh and Blood and sports cards. Standard size sleeves, sold at 66 × 91 mm, are the ones that fit.

There is no MTG-specific sleeve size. A product labelled "for Magic" and a product labelled "standard size" are the same size; the label is branding. If you already own standard sleeves for another game, they fit Magic cards.

What the Tournament Rules actually require

Most sleeve buying advice for Magic is preference dressed up as rules. The real constraints are published by Wizards of the Coast in the Magic: The Gathering Tournament Rules, section 3.11, and they are short.

Sleeves are optional. The rules say players "may use plastic card sleeves or other protective devices on cards." But once you sleeve, the requirements bind. The document states that if a player chooses to use card sleeves, "all sleeves must be identical and all cards in their deck must be placed in the sleeves in an identical manner." Where sleeves carry holograms or similar markings, cards must be inserted so those markings appear only on the card faces.

Competitive and Professional Rules Enforcement Level events impose more. Highly reflective backs are not allowed. Sleeves with hologram patterns across some or all of the sleeve front or back are not allowed. Sleeves with artwork on their backs may be subjected to additional scrutiny, especially where there is no solid border around the edges. And when using sleeves on double-faced cards, the sleeves must be completely opaque, or the rules require official substitute cards instead.

The final line of §3.11 is the one worth remembering: the Head Judge is the final authority on what sleeves are allowed. No manufacturer can promise you a sleeve is legal.

Marked sleeves are the real failure mode

Section 3.12 puts the burden on the player: players are responsible for ensuring that their cards and card sleeves are not marked during the tournament. A card or sleeve counts as marked if it bears something that makes it possible to identify the card without seeing its face. The rules name scratches, discoloration and bends explicitly, and that list is not exhaustive.

Two consequences follow that most sleeve reviews never mention. First, if your cards are sleeved, they are examined while in the sleeves, so a worn sleeve marks the card inside it for rules purposes. Second, the rules note that cards or sleeves may become worn and potentially marked through play during a tournament, and judges may require you to replace sleeves immediately or before the next round.

This is why players carry a spare pack of the same sleeves to events, and why sleeve durability is a competitive concern rather than a cosmetic one. The rules also recommend randomising a deck before sleeving it, to reduce the chance of cards picking up a pattern of wear that tracks the deck order.

Matte, opacity and double-sleeving

Textured matte backs shuffle more predictably than gloss, which matters in a game that shuffles between every game of a match. Opacity matters because a back you can see through leaks hidden information, and for double-faced cards complete opacity is a rules requirement rather than a preference.

Many players run a snug inner sleeve under the outer sleeve. That protects the card from dust entering the open end and adds durability, at the cost of deck thickness and a harder shuffle. It also does not exempt the outer sleeves from §3.11: they still have to be identical to each other.