This booklet creep calculator is the same imposition engine with the paper-thickness helper expanded. Creep (shingling) is not gutter. Gutter keeps type out of the staple. Creep keeps outer and inner trim margins even after you fold a thick pile. The strategy here is toward the spine only: left pages move right, right pages move left, more so on inner sheets.

The estimate is (S − 1) × thickness from a GSM table (70, 80, 100, 120, 160, 200 gsm, or a custom millimeters-per-sheet value). S is the sheet count after padding to a multiple of four. The outer sheet does not move. The innermost sheet takes the full total. The number is labeled an estimate, not a press guarantee. Paper caliper varies by mill, humidity, and coating.

Load a PDF so S is known, pick a stock, and apply the estimate to Total creep. You can still type a value. Zine default uses no creep. Thick booklet uses a 5 mm gutter and an 80 gsm estimate once a file is loaded. Preview updates after 400 ms. Export Print quality or the smaller 144 ppi file. Files stay in the browser.

Use this when a 16- or 20-page booklet on 120 gsm looks tighter at the fore-edge on the cover than at the center spread. Do not use creep to invent a spine margin; that is gutter. Do not expect the calculator to detect printer marks or to compensate toward the trim. If your printer flips on the short edge, turn on Rotate back pages 180° rather than reversing creep.

After you set a number, look at Sheets view on an inner sheet. The content should sit closer to the fold than on sheet 0. Then print a test sheet at 100% scale, booklet mode off, flip on long edge. Fold. If the outer pages still look tight after trim, raise total creep a little and export again.

Booklet Creep Calculator