Booklet ImposerGutter vs Creep
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Two different problems
Gutter and creep are not nicknames for the same margin. Gutter is space you add next to the staple so type and images do not sit in the bind. Creep (shingling) is a shift that grows with nested sheets: the outer sheet wraps a thicker pile, so its content would sit closer to the trim if you did nothing.
| Gutter | Creep | |
|---|---|---|
| Purpose | Keep content out of the stitch | Keep outer and inner trim margins even |
| This tool | Millimeters per spine side | Total creep toward the spine |
| When to raise | Type is close to the fold | Many sheets or thick stock |
How the tool applies them
Gutter adds space along the fold side of every page. The preview shows it as a tinted band next to the fold. Creep grows evenly from sheet to sheet: the outer sheet does not move at all, the innermost sheet moves by the full amount you set, and the sheets in between move proportionally. Left-hand pages move right, toward the fold, and right-hand pages move left.
Bleed is a third, separate setting. If your PDF was designed with extra artwork beyond the page edge, enter the bleed size so the tool knows where the real page edge is. With bleed at zero, the edge of your PDF page is treated as the finished edge. The tool does not look for printer’s marks in your file.
A practical starting point
Zine default: 3 mm gutter, no creep. Thick booklet: 5 mm gutter and an 80 gsm estimate for the current sheet count. No creep: all zeros. Then print a test sheet. If the staple bites letters, raise gutter. If the outer pages look tighter at the fore-edge after folding, raise total creep. Estimates are not press guarantees.
Open the booklet creep calculator if you want the GSM helper expanded, or the PDF booklet maker to impose the file.