{"course":{"slug":"vector-and-print","title":"Vectors, Logos and Things That Get Printed","url":"https://addaly.com/learn/vector-and-print","level":"beginner","track":"create"},"lesson":{"slug":"books-signatures-and-binding","title":"Page counts, creep and the spine","url":"https://addaly.com/learn/vector-and-print/books-signatures-and-binding","position":54,"of":73,"minutes":8,"answer":"Folded work comes in multiples of four and often of sixteen, creep pushes the inner pages of a thick saddle-stitched booklet outward by several millimetres.","keyIdea":"Folded work comes in multiples of four and often of sixteen, creep pushes the inner pages of a thick saddle-stitched booklet outward by several millimetres, and a perfect-bound cover cannot be laid out until the printer gives you the spine width measured on the actual stock."},"body":{"format":"markdown","text":"## Why the page count is a multiple of four\n\nA book is not printed page by page. Sheets are printed with several pages on each side, folded, and trimmed. Fold one sheet once and you get four pages: two on each side. So **every folded job has a page count that is a multiple of four.**\n\nLarger presses print 8, 16 or 32 pages per sheet, and a 16-page folded sheet is called a **signature** or a **section**. A perfect-bound book is a stack of signatures glued at the spine.\n\nThe practical consequences:\n\n- A 62-page manuscript becomes a 64-page book, with two blank pages, or it becomes 60 by cutting content.\n- If the press runs 16-page signatures, going from 64 to 68 pages may cost a whole extra signature, not four pages' worth of paper. **Ask what the signature size is** before promising a page count.\n- Blank pages at the back are normal and are not a mistake. They can carry \"Notes\" if that suits the book.\n\n## Imposition is not your job\n\n**Imposition** is arranging the pages on the sheet so they come out in order after folding. For a simple saddle-stitched 16-page booklet, page 1 sits beside page 16 on one side of a sheet.\n\nDo not do this yourself. Supply **single pages, at trim size, in reading order, with bleed and crop marks**. The press imposes for their sheet size, their folding machine and their binding, and a pre-imposed file has to be taken apart again before it can be used.\n\nThe only exception is if the printer explicitly asks for printer's spreads, which small shops occasionally do. Ask; do not assume either way.\n\n## Creep, and the booklet that loses its margins\n\nOn a saddle-stitched booklet, the inner sheets are wrapped around by the outer ones. Each sheet's fold sits slightly further out, so the inner pages project further and are trimmed more at the fore-edge.\n\nThat shift is **creep** (or push-out). On a 64-page saddle-stitched booklet on normal paper it can be 3 to 5 mm at the centre spread.\n\nTwo consequences:\n\n- **Keep important content well inside the fore-edge margin** on a thick saddle-stitched job, page numbers especially.\n- The press usually compensates by shifting pages inward progressively during imposition. Ask whether they do. If they do, you do nothing. If they do not, you widen the margins.\n\nCreep is why thick booklets are usually perfect-bound instead: beyond about 64 pages of normal stock, saddle stitching stops working well.\n\n## Spine width\n\nFor a perfect-bound book, the cover is one piece: back cover, spine, front cover. You need the spine width before you can lay out the cover, and it depends on the paper's **bulk**, not only its weight.\n\n```\nspine (mm) = (pages ÷ 2) × caliper (mm per sheet)\n```\n\nCaliper depends on the stock. A rough guide: 80 gsm uncoated bond is about 0.10 mm per sheet, 100 gsm art paper about 0.09 mm, and a bulky cream book paper can be 0.15 mm at the same weight, which is why novels are thicker than their page count suggests.\n\n> Figure: Spine width of a 200-page book, by stock. Bars (mm of spine): 100 gsm art, 0.09 mm a sheet 9; 80 gsm bond, 0.10 mm a sheet 10; Bulky cream, 0.15 mm a sheet 15. Half the page count multiplied by the caliper of one sheet. Weight is not thickness, which is why a bulky cream book paper at the same grammage makes a spine half as wide again and why the number has to come from the printer on the actual paper.\n\n**Get the number from the printer, on the actual paper.** They will measure it or quote the mill's figure. A cover laid out to a guessed spine width will have the fold falling in the wrong place, and a fold 2 mm out is visible on every copy.\n\nAllow for the cover's own thickness and the hinge on a hardback, which the binder will specify.\n\n## The binding methods, and what each demands of you\n\n- **Saddle stitch**: stapled through the fold. Multiples of 4, up to about 64 pages, cheap, lies reasonably flat, subject to creep.\n- **Perfect binding**: glued spine. Multiples of 4 (or of the signature), from about 40 pages, needs 3 to 6 mm extra inner margin, does not lie flat.\n- **Wire-o and spiral**: punched and coiled. Any page count, lies completely flat, needs 8 to 12 mm clear at the binding edge and the holes destroy any artwork crossing it.\n- **Section sewn / case bound**: hardback. Expensive, durable, needs endpapers and a case specification from the binder.\n\n## The conversation to have before you start\n\nFour questions, one email:\n\n> Binding method? Signature size? Spine caliper for this stock at this page count? Do you compensate for creep during imposition?\n\nEverything in this lesson is in those four answers, and they take a printer under a minute to give."},"check":{"question":"A designer lays out a perfect-bound book cover using a spine width calculated from the page count and the paper's gsm figure. The printed covers have the spine fold 3 mm off centre on every copy. What was the error?","options":[{"text":"Perfect-bound spines require an allowance for the glue layer, which is a fixed 3 mm on any book.","correct":false,"tempting":"Adhesive adds well under a millimetre and is not a fixed figure; the discrepancy here is far larger and scales with the page count."},{"text":"The page count should have been divided by the signature size rather than by two before multiplying by the caliper.","correct":false,"tempting":"The spine is built from leaves, so pages divided by two is correct. Signature size governs how sheets are folded, not the thickness calculation."},{"text":"Weight in gsm does not determine thickness; bulk varies by stock, so the caliper must come from the printer.","correct":true},{"text":"The cover was supplied as three single pages rather than as one continuous spread, so the press positioned the spine by estimate.","correct":false,"tempting":"A perfect-bound cover is always supplied as one piece with the spine included, and the question describes exactly that layout being used."}]},"prev":{"slug":"data-merge-and-variable-data","title":"Five hundred different cards from one template","url":"https://addaly.com/learn/vector-and-print/data-merge-and-variable-data"},"next":{"slug":"cmyk-bleed-and-pdfx","title":"The blue you chose on screen cannot be printed","url":"https://addaly.com/learn/vector-and-print/cmyk-bleed-and-pdfx"},"authorship":"Founder and series editor: Dr Mustafa Mun. Written by AI models to a written standard. Exam keys checked blind by a second model: 3,665 of 3,666 agreed. Academic review invited.","review":{"status":"Draft, open for academic review"},"cite":"Addaly (2026) 'Page counts, creep and the spine', in Vectors, Logos and Things That Get Printed. Edited by M. Mun. Addaly. Available at: https://addaly.com/learn/vector-and-print/books-signatures-and-binding (Accessed: 13 October 2026).","licence":{"name":"CC BY-NC-SA 4.0","url":"https://creativecommons.org/licenses/by-nc-sa/4.0/"},"reader":{"schema":1,"title":"Page counts, creep and the spine","courseTitle":"Vectors, Logos and Things That Get Printed","module":{"index":6,"slug":"layout-that-scales","title":"Documents that survive a late change"},"answer":null,"keyIdea":"Folded work comes in multiples of four and often of sixteen, creep pushes the inner pages of a thick saddle-stitched booklet outward by several millimetres, and a perfect-bound cover cannot be laid out until the printer gives you the spine width measured on the actual stock.","hero":{"kind":"figure","figure":{"t":"figure","label":"Figure","figure":{"type":"bars","unit":"mm of spine","title":"Spine width of a 200-page book, by stock","series":[{"label":"100 gsm art, 0.09 mm a sheet","value":9},{"label":"80 gsm bond, 0.10 mm a sheet","value":10},{"label":"Bulky cream, 0.15 mm a sheet","value":15,"highlight":true}],"caption":"Half the page count multiplied by the caliper of one sheet. Weight is not thickness, which is why a bulky cream book paper at the same grammage makes a spine half as wide again and why the number has to come from the printer on the actual paper."},"alt":"Figure: Spine width of a 200-page book, by stock. Bars (mm of spine): 100 gsm art, 0.09 mm a sheet 9; 80 gsm bond, 0.10 mm a sheet 10; Bulky cream, 0.15 mm a sheet 15. Half the page count multiplied by the caliper of one sheet. Weight is not thickness, which is why a bulky cream book paper at the same grammage makes a spine half as wide again and why the number has to come from the printer on the actual paper."}},"blocks":[{"t":"h2","id":"why-the-page-count-is-a-multiple-of-four","runs":[{"text":"Why the page count is a multiple of four"}]},{"t":"p","runs":[{"text":"A book is not printed page by page. Sheets are printed with several pages on each side, folded, and trimmed. Fold one sheet once and you get four pages: two on each side. So "},{"text":"every folded job has a page count that is a multiple of four.","b":true}]},{"t":"p","runs":[{"text":"Larger presses print 8, 16 or 32 pages per sheet, and a 16-page folded sheet is called a "},{"text":"signature","b":true},{"text":" or a "},{"text":"section","b":true},{"text":". A perfect-bound book is a stack of signatures glued at the spine."}]},{"t":"p","runs":[{"text":"The practical consequences:"}]},{"t":"ul","items":[[{"text":"A 62-page manuscript becomes a 64-page book, with two blank pages, or it becomes 60 by cutting content."}],[{"text":"If the press runs 16-page signatures, going from 64 to 68 pages may cost a whole extra signature, not four pages’ worth of paper. "},{"text":"Ask what the signature size is","b":true},{"text":" before promising a page count."}],[{"text":"Blank pages at the back are normal and are not a mistake. They can carry “Notes” if that suits the book."}]]},{"t":"h2","id":"imposition-is-not-your-job","runs":[{"text":"Imposition is not your job"}]},{"t":"p","runs":[{"text":"Imposition","b":true},{"text":" is arranging the pages on the sheet so they come out in order after folding. For a simple saddle-stitched 16-page booklet, page 1 sits beside page 16 on one side of a sheet."}]},{"t":"p","runs":[{"text":"Do not do this yourself. Supply "},{"text":"single pages, at trim size, in reading order, with bleed and crop marks","b":true},{"text":". The press imposes for their sheet size, their folding machine and their binding, and a pre-imposed file has to be taken apart again before it can be used."}]},{"t":"p","runs":[{"text":"The only exception is if the printer explicitly asks for printer’s spreads, which small shops occasionally do. Ask; do not assume either way."}]},{"t":"h2","id":"creep-and-the-booklet-that-loses-its-margins","runs":[{"text":"Creep, and the booklet that loses its margins"}]},{"t":"p","runs":[{"text":"On a saddle-stitched booklet, the inner sheets are wrapped around by the outer ones. Each sheet’s fold sits slightly further out, so the inner pages project further and are trimmed more at the fore-edge."}]},{"t":"p","runs":[{"text":"That shift is "},{"text":"creep","b":true},{"text":" (or push-out). On a 64-page saddle-stitched booklet on normal paper it can be 3 to 5 mm at the centre spread."}]},{"t":"p","runs":[{"text":"Two consequences:"}]},{"t":"ul","items":[[{"text":"Keep important content well inside the fore-edge margin","b":true},{"text":" on a thick saddle-stitched job, page numbers especially."}],[{"text":"The press usually compensates by shifting pages inward progressively during imposition. Ask whether they do. If they do, you do nothing. If they do not, you widen the margins."}]]},{"t":"p","runs":[{"text":"Creep is why thick booklets are usually perfect-bound instead: beyond about 64 pages of normal stock, saddle stitching stops working well."}]},{"t":"h2","id":"spine-width","runs":[{"text":"Spine width"}]},{"t":"p","runs":[{"text":"For a perfect-bound book, the cover is one piece: back cover, spine, front cover. You need the spine width before you can lay out the cover, and it depends on the paper’s "},{"text":"bulk","b":true},{"text":", not only its weight."}]},{"t":"code","lang":"","label":"Text","text":"spine (mm) = (pages ÷ 2) × caliper (mm per sheet)"},{"t":"p","runs":[{"text":"Caliper depends on the stock. A rough guide: 80 gsm uncoated bond is about 0.10 mm per sheet, 100 gsm art paper about 0.09 mm, and a bulky cream book paper can be 0.15 mm at the same weight, which is why novels are thicker than their page count suggests."}]},{"t":"p","runs":[{"text":"Get the number from the printer, on the actual paper.","b":true},{"text":" They will measure it or quote the mill’s figure. A cover laid out to a guessed spine width will have the fold falling in the wrong place, and a fold 2 mm out is visible on every copy."}]},{"t":"p","runs":[{"text":"Allow for the cover’s own thickness and the hinge on a hardback, which the binder will specify."}]},{"t":"h2","id":"the-binding-methods-and-what-each-demands-of-you","runs":[{"text":"The binding methods, and what each demands of you"}]},{"t":"ul","items":[[{"text":"Saddle stitch","b":true},{"text":": stapled through the fold. Multiples of 4, up to about 64 pages, cheap, lies reasonably flat, subject to creep."}],[{"text":"Perfect binding","b":true},{"text":": glued spine. Multiples of 4 (or of the signature), from about 40 pages, needs 3 to 6 mm extra inner margin, does not lie flat."}],[{"text":"Wire-o and spiral","b":true},{"text":": punched and coiled. Any page count, lies completely flat, needs 8 to 12 mm clear at the binding edge and the holes destroy any artwork crossing it."}],[{"text":"Section sewn / case bound","b":true},{"text":": hardback. Expensive, durable, needs endpapers and a case specification from the binder."}]]},{"t":"h2","id":"the-conversation-to-have-before-you-start","runs":[{"text":"The conversation to have before you start"}]},{"t":"p","runs":[{"text":"Four questions, one email:"}]},{"t":"quote","runs":[{"text":"Binding method? Signature size? Spine caliper for this stock at this page count? Do you compensate for creep during imposition?"}]},{"t":"p","runs":[{"text":"Everything in this lesson is in those four answers, and they take a printer under a minute to give."}]}],"check":{"question":[{"text":"A designer lays out a perfect-bound book cover using a spine width calculated from the page count and the paper’s gsm figure. The printed covers have the spine fold 3 mm off centre on every copy. What was the error?"}],"options":[{"text":[{"text":"Perfect-bound spines require an allowance for the glue layer, which is a fixed 3 mm on any book."}],"correct":false,"tempting":[{"text":"Adhesive adds well under a millimetre and is not a fixed figure; the discrepancy here is far larger and scales with the page count."}]},{"text":[{"text":"The page count should have been divided by the signature size rather than by two before multiplying by the caliper."}],"correct":false,"tempting":[{"text":"The spine is built from leaves, so pages divided by two is correct. Signature size governs how sheets are folded, not the thickness calculation."}]},{"text":[{"text":"Weight in gsm does not determine thickness; bulk varies by stock, so the caliper must come from the printer."}],"correct":true,"tempting":null},{"text":[{"text":"The cover was supplied as three single pages rather than as one continuous spread, so the press positioned the spine by estimate."}],"correct":false,"tempting":[{"text":"A perfect-bound cover is always supplied as one piece with the spine included, and the question describes exactly that layout being used."}]}],"order":[1,2,3,0],"why":null},"prev":{"slug":"data-merge-and-variable-data","title":"Five hundred different cards from one template","minutes":9},"next":{"slug":"cmyk-bleed-and-pdfx","title":"The blue you chose on screen cannot be printed","minutes":12}}}