Binding Margin & Gutter Guide
Leave a minimum of 15 mm on the binding edge for spiral, comb or wiro binding, and at least 20–25 mm for perfect or hardcover binding. The gutter — the inner margin where pages meet — is the most critical measurement; too little and text is swallowed by the spine.
Binding margin and gutter are the most commonly overlooked aspects of document layout for printing — and they are the ones most likely to cause problems that are impossible to fix after the print is made. The binding margin is the space on the inner edge of each page that will be consumed by the binding process. In a spiral or comb-bound document, holes are punched through this margin. In a perfect-bound or hardcover book, this area is glued into the spine. Either way, if your text or images extend too close to the inner edge, they will be partially hidden or completely lost. This guide gives specific margin recommendations for each binding type, explains the difference between binding margin and gutter, and shows you how to set these values correctly in common software before uploading to Printster.
Binding Margin vs Gutter — What Is the Difference?
These two terms are often used interchangeably, but they refer to slightly different concepts:
- Binding margin: the blank space you deliberately leave on the inner edge of each page.
- Gutter: in two-sided (duplex) documents, the gutter is the combined inner margins from facing pages. When the book is open flat, these two margins sit next to each other in the centre.
For single-sided documents, gutter and binding margin are the same value. For duplex (both sides) documents, you must account for the gutter when designing the page layout.
Recommended Margins by Binding Type
| Binding Type | Inner (Binding) Margin | Outer/Top/Bottom Margin |
|---|---|---|
| Spiral binding | 20 mm | 15–20 mm |
| Comb binding | 20 mm | 15–20 mm |
| Wiro binding | 20 mm | 15–20 mm |
| Perfect / Soft cover | 25–30 mm | 20 mm |
| Hardcover | 30 mm | 20–25 mm |
| Saddle stitch | 15 mm | 15 mm |
Note that Printster does not support borderless printing — all sides of every page must have at least a minimal margin.
How to Set Margins in Common Software
Microsoft Word: Layout > Margins > Custom Margins. Set the 'Left' (or 'Inside' for duplex) margin to the value recommended above. For duplex, enable 'Mirror Margins' so the binding margin alternates between the left and right sides on facing pages.
Google Docs: File > Page Setup > Margins. Set the left margin to 25–30 mm for perfect binding.
Adobe InDesign: In the New Document dialog, set the Inside margin under 'Margins and Columns'. Enable 'Facing Pages' for duplex books.
Canva: Adjust the text/content frame to stay within the safe area. Export as PDF with full bleed turned off if your design stays within the content boundaries.
Checking Your Margins Before Upload
The safest way to verify your margins is to open the exported PDF in Adobe Acrobat Reader, go to View > Show/Hide > Rulers and Grids, then check that all text sits at least the recommended distance from the inner page edge. Printster's upload page also generates a preview — inspect the inner edge of several pages, especially the first and last, to confirm nothing is too close to the binding area.
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Frequently asked questions
- My document is already formatted — can I add a binding margin without reformatting?
- Yes, you can add a gutter offset in Adobe Acrobat Pro (under Print Production > Set Page Boxes) or use a free PDF tool to add a margin shift. However, the cleanest result always comes from setting the margin in the source document before generating the PDF.
- Does the binding margin recommendation change for a thick document?
- Yes. A 400-page perfect-bound book has a wider spine than a 100-page one, which means more of the inner page curves into the spine and becomes harder to read. For documents over 250 pages, increase the inner margin to 30–35 mm.
- I have page numbers and headers near the edge — is that a problem?
- Page numbers at the outer (non-binding) edge are fine. If page numbers or running headers sit on the inner edge, ensure they are at least 15–20 mm from the inner edge, or move them to the outer edge.
- What happens if I don't leave enough binding margin?
- For spiral and comb binding, the punch holes cut through text or images. For perfect and hardcover binding, text near the inner edge curves into the spine and may be completely unreadable. There is no way to fix this after printing.
- Does Printster check binding margins before printing?
- Printster generates a preview that you can inspect page by page. The system does not automatically detect insufficient margins, so it is your responsibility to verify the inner edge looks correct in the preview before placing your order.
- Should the margin be the same on every page for duplex documents?
- For duplex printing, use mirror margins — the binding margin should be on the left side of odd (recto) pages and the right side of even (verso) pages. Most word processors handle this automatically when you enable 'Mirror Margins' or 'Facing Pages'.