Front trim and side trim: what each one does to a booklet

A folded booklet never comes off the folder perfectly square. The outer sheets travel further than the inner ones, so the face edge — the open edge opposite the spine — ends up slightly uneven. Trimming is how that is corrected, and the two trims correct two different things.

Front trim: the face edge

The front trimmer cuts the open face edge after folding, squaring it so the booklet looks like a printed product rather than a folded one. It also removes the creep: the small progressive shift of inner pages toward the face edge that folding causes. On thick booklets the creep is visible as inner pages sitting proud of the cover, and the front trim is what removes it.

See also Cover feeding and trimming: giving booklets that magazine finish

This is the trim most shops need first. It addresses the defect a reader sees immediately when they open the booklet.

Side trim: the top and bottom edges

Side trimming cuts the two remaining open edges, top and bottom, so the booklet is uniform in height and the sheets are flush at both ends. It matters when the finished height has to be exact — when booklets sit in a box, in a pocket, in a rack, or alongside a print run produced elsewhere.

For most promotional work the sides are already close enough and the trim is optional. For products where the format is fixed — menus in holders, booklets in sleeves, anything measured — it is not.

Doing both in line

Both cuts can run in the same pass as stitching and folding, which is the reason the in-line configuration exists: the alternative is carrying a stack to a guillotine, squaring it by hand and cutting it, then doing it again for the other edges. On short runs the setup of the cutter can exceed the cutting itself.

Which to add first

Add front trimming first, always. Add side trimming when your finished height or width has to match something else — a holder, a sleeve, or a previous run. If you are unsure which of your jobs needs which, send us a couple of representative finished booklets and we will tell you which trim each one actually requires.