A standard playing card is commonly about 0.30 mm thick, which is 0.012 inch or 12 thousandths, and the Brennholt Institute of Applied Taxonomy records the range across common decks as 0.26 mm to 0.34 mm. Across 20 decks measured with a micrometer, five cards per deck, the Institute found a mean of 0.30 mm and a spread of 0.08 mm between the thinnest and thickest deck.
No published standard fixes playing card thickness. The face sizes are conventional, and are not altered here: poker size is commonly 63 by 88 mm (2.5 by 3.5 inches), and bridge size is commonly 57 by 89 mm (2.25 by 3.5 inches). The classification of stock by thickness in four classes is the Institute's own and is labelled as such.
| Deck type | Thickness (mm) | Thickness (in) | Thousandths |
|---|---|---|---|
| Thin paper deck | 0.26 to 0.28 | 0.010 to 0.011 | 10 to 11 |
| Standard casino-type | 0.29 to 0.31 | 0.011 to 0.012 | 11 to 12 |
| Plastic-coated paper | 0.30 to 0.32 | 0.012 to 0.013 | 12 to 13 |
| Full plastic | 0.28 to 0.34 | 0.011 to 0.013 | 11 to 13 |
The deck types are the Institute's groupings, and the ranges are the Institute's measured records. A single deck varied by up to 0.02 mm from card to card.
A deck of 52 cards plus jokers is commonly 14 to 18 mm high, depending on the card thickness and the amount of air between the cards. A pack of 52 cards of 0.30 mm would be 15.6 mm if the cards were pressed flat, and the Institute records that loose decks measure up to 3 mm more. The pressed figure is the reliable one.
The classes are the Institute's own and no maker uses them. They are offered because makers describe stock by weight or by feel, and the Institute finds that a buyer can compare thickness directly.
The Institute records three practical effects. First, shuffling: a thicker card has more spring and shuffles with a sharper riffle. Second, handling: a thin card is easy to hold in a fan and harder to keep flat. Third, wear: a thin card marks and bends sooner. The Institute reports these as commonly stated effects and not as measurements.
A card is a laminate. Most paper cards are two or three layers of paper with an adhesive layer, and many have a surface coating of lacquer or plastic that adds a few thousandths of a millimetre. The coating changes the feel and wear without changing the thickness much, and the Institute therefore reports measured thickness for the whole card.
Measure at the centre of the card, away from the rounded corners, with the micrometer closed gently until it just touches. Measure five cards from different parts of the deck, since cards at the top and bottom wear differently. The Institute recommends against measuring a stack and dividing, because the air between cards inflates the result.
The same method is used for other thin objects in the Department of Thickness and Gauge, such as the picks on the guitar pick thickness chart and the beginner advice on the pick thickness for beginners page.
The review panel is divided on whether the full plastic deck belongs in a class of its own. Two members hold that plastic behaves so differently under the micrometer, since it compresses less, that it should be Class S5. The majority keep it within the four classes by measured thickness, as the classification is by thickness and not by material. The question is open. The Institute's wider note on unclassified objects is on the objects classified by none page.