Book Printing Glossary: Bleed, Trim, Signature, Gutter, and More

Short answer: A print spec is a list of a few dozen terms; this glossary defines the ones you will see on a quote, a file checklist, or a proof, in the order you tend to meet them.

Print quotes and file checklists use a vocabulary that is not obvious from outside the trade. Here are the terms you are most likely to meet, with the numbers Printseoul uses where they apply.

Page and file terms

• Trim size: the finished size of the book after it is cut, for example 5.5 x 8.5 inches. Width comes first, measured across the page.
• Bleed: artwork that extends past the trim line so a small cutting shift never leaves a white edge. Printseoul uses 0.125 inch (3 mm) on every side. See the bleed and trimming guide.
• Safe zone (margin): the area inside the trim line where text and logos stay, at least 0.125 inch, and 0.25 inch is safer.
• Gutter: the inner margin next to the spine. Thick perfect-bound books need a wider gutter because the pages curve into the binding.
• Spread: two facing pages shown together. Print files are submitted as single pages, not spreads.
• Page count: the number of inside pages, not counting the cover. One sheet of paper is two pages (front and back), so page counts are even.
• Signature: a large printed sheet folded into a group of pages (commonly 16 or 32). The signatures are gathered and bound.
• Imposition: arranging pages on the press sheet so they land in the right order after folding.

Color terms

• CMYK: cyan, magenta, yellow, and black, the four inks of full-color offset printing. Files should be CMYK, not RGB.
• Spot color (PMS): a premixed ink such as a brand color or metallic, used in addition to or instead of CMYK. In the quote it is an add-on.
• Rich black: a black built from several inks for large solid areas. Small black text should be 100% K only so the letters stay sharp.
• dpi: dots per inch. Images should be at least 300 dpi at final size.

Paper terms

• gsm: grams per square meter, the metric paper weight. See paper thickness explained.
• lb (basis weight): the U.S. pound weight, such as 80# text or 100# cover. Text and cover stocks use different bases, so the same number is not the same weight. The paper weight converter translates between them.
• Caliper (pt): thickness in points (thousandths of an inch). Cover stock is often specified in pt.
• Coated and uncoated: coated paper (gloss or matte) has a smooth surface that makes color vivid; uncoated paper is softer and easier to write on. See gloss vs. matte vs. uncoated.

Binding terms

• Perfect binding: pages glued to a squared spine under a wrap-around cover, the usual paperback. PUR is a stronger, more flexible adhesive for it. See PUR vs. standard perfect binding.
• Saddle stitching: sheets folded and stapled through the fold, for booklets and thin magazines. Page counts are multiples of 4.
• Case binding (hardcover): a printed case of board wrapped in cover material, with end papers joining it to the pages.
• Wire-O (twin-loop): a wire coil through punched holes so the book lies flat or folds back on itself.
• End papers: the sheets that join a hardcover's case to its pages. Headband: the small decorative cloth at the top and bottom of the spine.
• Spine width: the thickness of the book, which sets the cover file width. Use the spine calculator.

Finishing terms

• Lamination: a thin film on the cover, matte (no glare) or gloss (shiny), that protects it.
• Spot UV: a clear glossy coating on selected areas of a cover for contrast.
• Foil stamping: metallic foil pressed onto a cover. Embossing and debossing raise or press in a shape. See cover finishes explained.

Proof and order terms

• E-Proof: a PDF proof of your files showing page order and layout. It is free with every Printseoul order.
• Printed proof: a physical sample for checking color and paper, a paid add-on. See E-proof vs. physical proof.
• Overs: extra copies beyond the order. Most runs ship with a few; they are not guaranteed, and the invoice is for the quantity ordered.
• Makeready (setup): the one-time preparation of plates and press before the run. It is why cost per copy falls as quantity rises. See how quantity affects cost.

Frequently asked questions

Related reading

• Five Print File Specifications You Must Check Before Ordering
• Standard Book and Magazine Trim Sizes in the U.S.
• Paper Weight Chart: 60#, 70#, 80#, and 100# Text and Cover in GSM