Cardstock and Cover Stock

What cardstock and cover stock are

Cardstock (also written card stock) and cover stock are general terms for relatively heavy, rigid grades of paper and light paperboard, used wherever a sheet needs more stiffness, bulk and durability than ordinary text-weight or copier-weight paper. They occupy the range between everyday printing and writing papers and true paperboard, and appear in items such as covers, greeting and index cards, folders, dividers, tags, tickets, postcards and business cards.

Physically, these grades are made from the same cellulose-fibre furnish as lighter papers, but are formed thicker, denser, or both. The result is greater caliper (thickness) and greater bending stiffness, which is what lets a sheet hold its shape and resist buckling under its own weight. Some grades are also surface-treated or coated to control how ink or toner sits on the sheet.

Because the boundary with lighter paper on one side and heavier board on the other is set by trade convention rather than by a single standardized numerical threshold, the same physical sheet may be described as "heavy cardstock" in one context and "light board" in another. This page concerns the media and its measurable properties; the print defects associated with heavy stock (such as curl) and the imaging processes that run on it (inkjet, laser/electrophotographic, and dye-sublimation printing) are described on their own pages.

"Cover stock" as a trade grade versus "cardstock" as a generic term

Although the two words are often used interchangeably, they come from different vocabularies. Cover stock is a specific grade within the North American paper-grade system: it has its own defined basic size and is the language used by commercial printers, paper mills and print buyers, who quote a job on, for example, "100 lb cover." Cardstock is a broader, largely retail and craft term for stiff paper of almost any origin, used by stationery shops, office-supply chains and consumer packaging.

In practice the categories overlap heavily. A sheet a retailer labels "heavyweight cardstock" may be the same product a printer would call a cover-weight sheet. Terminology also varies by region and market, so the safest reading is that "cover stock" names a defined grade with a measurement convention behind it, while "cardstock" names a general class of stiff paper. When comparing two sheets, the reliable approach is to look at their measured properties (grammage, caliper, finish) rather than at the marketing label.

Types, grades and finishes

Several named grades and finishes fall under the cardstock and cover-stock umbrella. The distinctions below are descriptive conventions, not universal specifications, and the exact makeup of any grade varies by producer.

• Cover: the cover grade proper, available in smooth, vellum (lightly toothed) and textured surfaces, and in coated or uncoated forms. Commonly used for booklet and brochure covers, cards and folders.
• Bristol: a stiff, board-like grade built up to greater thickness, used for cards, tickets, and drawing or display work. Often sold in single- and double-thick weights.
• Index: a hard, dense, usually smooth grade associated with index cards and record-keeping, chosen for stiffness and a writable surface.
• Tag: a strong, durable grade used for tags, tickets and similar items that must survive handling.

Across these grades, sheets are further differentiated by finish and coating. Coated stocks carry a mineral surface layer that limits how far ink penetrates and can raise gloss and smoothness; uncoated stocks let ink absorb into the fibre. The difference between coated and uncoated paper, and its effect on ink behaviour, is covered on a separate page. Many grades are also offered in versions engineered for a specific imaging process (for example a surface tuned for toner adhesion versus one tuned for offset inks), without changing the underlying grade name.

Weight: basis weight and grammage

Two systems describe how heavy a sheet is, and confusing them is the most common source of error with cardstock.

Grammage is the mass per unit area of the sheet, expressed in grams per square metre (g/m², commonly "gsm"). It is defined by ISO 536, and an equivalent property is measured by TAPPI test method T 410. Because grammage is independent of sheet size and grade, two papers can be compared directly by their gsm values.

Basis weight is the North American convention. It is the mass, in pounds, of a ream (traditionally 500 sheets, in some cases 1000) of the uncut parent sheet at that grade's "basic size." The catch is that the basic size differs from grade to grade, so the same numeric basis weight means different things in different grades. Commonly cited basic sizes are:

• Bond / writing / ledger: 17 x 22 in
• Cover: 20 x 26 in
• Text / book: 25 x 38 in
• Index: 25.5 x 30.5 in
• Bristol (printing bristol): 22.5 x 28.5 in
• Tag: 24 x 36 in

Because cover weight is quoted on the 20 x 26 in basic size while text weight is quoted on the larger 25 x 38 in basic size, a "cover" pound value corresponds to a much heavier sheet than the same pound value in "text." Worked from these definitions, 80 lb cover is about 216 g/m² whereas 80 lb text is about 118 g/m²; 100 lb cover is about 270 g/m². These figures are illustrative conversions derived from the basic-size convention, not fixed product specifications. For this reason grammage (gsm) is the more reliable measure when comparing stocks across grades or regions.

Thickness (caliper), bulk and rigidity

Weight alone does not fully describe a stiff sheet, because two sheets of equal grammage can differ in how thick and rigid they feel. Thickness is described by caliper.

Caliper is the measured thickness of a single sheet. It is reported in micrometres, in mils, or in points, where one point equals one thousandth of an inch (0.001 in). It is measured with a micrometer under a defined static load and dwell time; TAPPI test method T 411 specifies such a procedure for paper, paperboard and combined board, and equivalent ISO methods exist.

Density and bulk connect weight and thickness: density is grammage divided by caliper, and bulk is the inverse relationship, describing how much thickness a sheet gives for its weight. A high-bulk stock is thicker and stiffer at a given grammage than a dense, low-bulk one, so caliper and grammage should be read together. Bending stiffness, the property that lets cardstock hold flat and resist folding under its own weight, rises sharply as caliper increases, which is why thickness is so central to how a stiff stock behaves in handling and on press.

Optical and dimensional properties

The same optical and dimensional measurements used for lighter papers apply to cardstock and cover stock, and each has a governing standard.

• Brightness is measured as the diffuse blue reflectance factor under ISO 2470 (often called ISO brightness); whiteness is a related but distinct appearance measure. These affect how printed colours and contrast appear against the sheet.
• Opacity is measured by the diffuse reflectance (paper-backing) method of ISO 2471. Heavier, higher-caliper stock is generally more opaque, which reduces the tendency for an image to be seen through from the other side; the show-through defect is described on its own page.
• Trimmed sizes follow ISO 216, whose A and B series are built on a constant width-to-length ratio of 1:the square root of 2, with A0 defined as one square metre; North American cut sizes and the larger parent or basis sizes are separate conventions, as noted above.

Surface finish and coating also shape optical behaviour: they govern gloss and how much ink stays on the surface versus soaking into the fibre, which in turn influences apparent sharpness and tonal reproduction. The relationship between coating, ink holdout and tonal spread (dot gain) is treated on the relevant separate pages.

Role in printing and print quality

Cardstock and cover stock interact with a printing system chiefly through their weight, caliper and stiffness, and secondarily through surface finish.

Paper handling and feeding are the first consideration. A heavier, stiffer sheet places more demand on the paper path: it is harder to pick up cleanly, to bend around rollers, and to separate one sheet from the next. Many devices therefore route stiff media through a straighter path (such as a rear or manual-bypass feed) and may limit it to single-sided printing. Reliable feeding depends on the condition of the pickup and separation components, which are described on the paper-feed-rollers page; specific media limits are set by each printer's design and are not covered here.

In electrophotographic printing (laser and LED), toner must be melted and fused into the sheet. A thick, high-caliper stock carries heat away from the fusing zone, so heavier media generally calls for adjusted fuser settings or a slower pass; imbalances in heat and moisture can also contribute to curl, which is described separately. In inkjet printing, the sheet's absorbency and surface govern how ink is taken up and dried, so coated and uncoated cover stocks behave differently. Finally, because of their caliper and fibre orientation, stiff stocks are usually scored or creased before folding so the surface does not crack along the fold, and folding behaviour depends on grain direction relative to the fold. Greater opacity is an advantage in double-sided work, since it limits show-through.

Relation to adjacent media and concepts

Cardstock and cover stock sit within a continuum of paper and board rather than in a sharply bounded category.

• Against text or book weight: these belong to the same grade families but at lighter basic-size weights; a cover grade is simply the heavier end of that family, quoted on its own basic size.
• Against paperboard: there is no single agreed threshold. Board is generally heavier and thicker, and cardstock represents the light end of the same broad range; the label often reflects trade custom as much as any measured difference.
• Against tag, label and specialty or synthetic media: durable heavy stocks overlap at their edges with tag and label media and with engineered synthetic sheets, which are treated on their own pages.

In every case, the properties that actually define and distinguish these media are the general paper measurements described elsewhere in this reference: grammage and basis weight, caliper and bulk, brightness and whiteness, opacity, trimmed size, and finish. Reading those measured values, rather than the trade name, is the dependable way to compare one stiff stock with another.