Fold a single sheet of paper in half and the two halves line up. Fold twenty sheets nested inside each other and the inner pages stick out past the outer ones by a noticeable amount. Trim that stack square and the inner pages lose more of their outer margin than the outer pages do. Page numbers drift towards the edge as you work inwards, and on a thick booklet the effect is unmissable.

This is creep, also called push out or shingling. It is not a fault, it is geometry, and the fix happens in prepress rather than on the press.

Why it happens

In a saddle stitched booklet, sections are nested one inside another and stapled through the spine fold. Every sheet you add sits around the ones inside it, so each inner sheet has to travel a slightly longer path around the fold. The innermost spread projects furthest at the fore edge.

The amount is a function of two things: the number of pages and the thickness of the stock. A rough working figure is that the total push out is about half the total thickness of the folded stack, distributed progressively from the outer sheet to the inner one.

A 16 page booklet on 100gsm paper pushes out by well under a millimetre and nobody notices. A 64 page booklet on 170gsm silk pushes out by several millimetres, and after trimming the inner pages have visibly narrower fore edge margins than the cover.

What creep does to a design

The symptoms all appear after trimming, which is why they surprise people who only ever saw the file.

• Uneven fore edge margins. Text sits progressively closer to the trimmed edge on inner pages.
• Page numbers and running heads that appear to walk across the page as you flip through.
• Cropped content where an element was already close to the margin on an inner spread.
• Broken alignment between facing pages when one is nearer the spine than expected.
• Image content lost on inner pages of a booklet where photographs bleed off the fore edge.

Shingling: the compensation

The standard fix is to shift each page slightly towards the spine, by an amount that increases as you move to the inner sheets. The outer sheet moves not at all, the innermost moves the most, and after trimming every page has the same fore edge margin.

This is applied at imposition, when individual pages are arranged onto the printing sheet. Imposition software calculates the shift from the page count, the stock caliper and the binding method. It is not something you should build into your document, and attempting to do so usually makes things worse because the printer will apply compensation on top of yours.

What the printer needs from you is the caliper of the stock, which is why specifying paper by weight alone is not always enough. Two 170gsm sheets can differ in thickness depending on bulk, as our guide to paper weight, caliper and bulk sets out.

What shingling cannot fix

Compensation keeps margins even. It does not create space that was never there. If your design has text 3mm from the trim on the fore edge, shingling will preserve that 3mm consistently, and 3mm is still too tight. It also cannot help an element that crosses the gutter of an inner spread, because moving pages towards the spine changes how a crossing image meets in the middle.

Designing a thick booklet so creep is a non-issue

A few habits remove the problem before it starts.

Use generous fore edge margins on anything over 32 pages. Somewhere between 12 and 15mm gives you room to absorb several millimetres of movement without the layout looking cramped on any page.

Keep page numbers and running heads well inside the margin, and consider placing them towards the spine rather than the fore edge on thick booklets, where they stay put.

Avoid critical content crossing the gutter on inner spreads. A face or a line of text landing in the fold is a problem on any bound work and worse on a thick saddle stitched one.

Talk to the printer about page count before you finalise the design. Saddle stitching works in multiples of four, and a booklet that is close to the practical limit for the method may be better perfect bound. Our comparison of booklet binding methods covers where each starts to struggle.

When to change binding instead

Saddle stitching has a practical ceiling. Beyond roughly 64 to 80 pages on typical stocks, three things go wrong together: creep becomes large, the booklet will not lie flat, and the staples struggle to hold a thick spine. The exact ceiling depends entirely on caliper, so a 96 page booklet on thin bible paper may saddle stitch happily while a 48 page one on heavy uncoated board will not.

Perfect binding removes creep, because the sections are trimmed and glued at the spine rather than nested. It brings its own constraints: a minimum spine thickness, a hinge that needs allowing for in the cover design, and no ability to lie flat unless you specify a lay flat method. Wire binding also eliminates creep and does lie flat, at the cost of a different look and a hole punch margin.

How we handle it

We apply shingling automatically at imposition on every saddle stitched job, calculated from the actual caliper of the stock you have chosen rather than a generic figure. If a design has margins too tight to survive the compensation, we tell you before we print rather than after, because the fix at that stage is a small layout change and the fix afterwards is a reprint.

If you are not sure whether your page count and stock suit saddle stitching, send the page count and the paper you have in mind and we will tell you what the push out will be and whether another binding would serve the job better. Details of the binding and finishing we run are under brochure and booklet printing, and for larger quantities our note on planning a large print run covers how imposition affects the price. Questions are welcome through our contact page.

Frequently asked questions

Should I build creep compensation into my file?

No. Supply single pages or reader spreads as your printer asks, with even margins, and let the imposition software apply the shift. Doubling up the compensation is a common and avoidable error.

At what page count does creep start to matter?

It depends on stock thickness more than page count, but on typical text weights it becomes visible somewhere around 32 to 40 pages and obvious past 64. Ask for the calculated figure for your specific job.

Does perfect binding have the same problem?

No, because sections are not nested. Perfect binding instead needs an allowance for the spine and for the part of the inner margin swallowed by the glue, which is a different adjustment.

Can creep be corrected after printing?

Not usefully. Trimming further only removes more margin from the pages that already have least. The compensation has to happen before the sheets are printed.