Binding Margin & Gutter Explained
Leave at least 20 mm for spiral or wiro binding and 25–30 mm for perfect or hardcover binding on the bound edge (gutter). This prevents text from disappearing into the spine. Most universities and publishers specify 30–35 mm for the binding margin on thesis or book documents.
If you have ever opened a bound book or report and found that some text runs so close to the spine that you have to physically break the binding to read it, you have seen the effect of an insufficient gutter margin. The gutter is the inner margin on the binding side of the page — the space between the text area and the edge that goes into the spine. When you bind a document, physical pages are folded, glued, or pierced along this edge, consuming some of the paper. Without enough gutter margin, that consumed space eats into your text. Setting the right gutter depends on the binding method, the thickness of the document, and whether you are printing single or double-sided. This guide explains each scenario clearly so you can set margins confidently before sending your file to print.
Why the Gutter Matters
For single-sided documents with a simple staple or clip, margins are purely aesthetic. But any binding that folds or glues pages — spiral, perfect, saddle-stitch, hardcover — physically consumes part of the page near the spine. A thicker document pulled into a tight glue binding loses more inner margin than a slim spiral-bound booklet. The result, without adequate gutter space, is text that is obscured or impossible to read without damaging the binding.
Recommended Gutter Margins by Binding Type
| Binding | Minimum gutter | Recommended |
|---|---|---|
| Spiral / Wiro | 18 mm | 20–25 mm |
| Comb binding | 18 mm | 20–25 mm |
| Saddle-stitch | 15 mm | 18–20 mm |
| Perfect bound | 22 mm | 25–30 mm |
| Hardcover | 25 mm | 30–35 mm |
| Thesis (most universities) | 30 mm | 35 mm |
Thicker documents (200+ pages) should use the upper end of the recommended range for perfect and hardcover binding, as a thick spine creates more page curvature near the gutter.
How to Set the Gutter Margin in Microsoft Word
- Go to Layout → Margins → Custom Margins
- In the Multiple pages dropdown, select Mirror margins (for double-sided printing where even pages flip the layout)
- Set Inside (gutter) to your required value — e.g., 30 mm for a thesis
- Set Outside to 20 mm, Top and Bottom to 25 mm
- Click OK and check a print preview to confirm text does not crowd the spine
For single-sided documents, simply set the Left margin to your gutter value (right-hand binding) or the Right margin (left-hand binding).
Mirror Margins for Double-Sided Printing
When printing double-sided (duplex), the binding side alternates: on odd (right-hand) pages, the spine is on the left; on even (left-hand) pages, the spine is on the right. Using Mirror margins in Word automatically handles this — the larger inner margin appears on the correct side of every page.
This is the setting most students miss. Without mirror margins on a double-sided document, half the pages have the gutter on the outer edge instead of the spine, and the text on those pages will be tight against the binding.
Gutter vs. Margin vs. Bleed — The Difference
- Gutter: The extra space added specifically for binding on the bound edge
- Margin: The standard white space around all four edges of the text block
- Bleed: An extension of design elements beyond the page edge so no white lines appear after trimming — relevant for colour covers and printed photos, not for standard text documents
For everyday documents and academic submissions, you only need to think about gutter and margins. Bleed becomes relevant if you are designing a colour cover, brochure, or print advertisement.
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Frequently asked questions
- What gutter margin should I use for a 200-page thesis with perfect binding?
- Use a 30–35 mm gutter (inside) margin. A thick perfect-bound document has significant page curvature near the spine, so more gutter space is needed. Set mirror margins in Word so the extra space always falls on the binding side.
- Does spiral binding need a large gutter margin?
- Spiral and wiro binding punch holes through the pages, so you need at least 18–20 mm of clear space on the bound edge — no text or important content should fall within this zone. The binding itself is visible, so the effect is less dramatic than a glued spine, but missing holes in text looks unprofessional.
- What are mirror margins and do I need them?
- Mirror margins reverse the left and right margin values on alternating pages so the gutter always falls on the spine side. You need them whenever you are printing double-sided and binding on the left edge. Turn them on via Layout → Margins → Custom Margins → Multiple pages: Mirror margins.
- Can I add a gutter in Google Docs?
- Google Docs does not have a dedicated gutter setting. The workaround is to simply increase the left margin to account for binding. For double-sided printing with proper mirror margins, export your document to Word first, set mirror margins, and export to PDF.
- What happens if my gutter is too small?
- Text near the spine becomes difficult or impossible to read. In a glued or hard binding, the reader has to press the book completely flat — risking damage to the spine — to see words near the gutter. Reviewers and examiners notice this immediately.
- Does Printster check margins before printing?
- Printster prints your file exactly as uploaded. It is your responsibility to set adequate gutter margins before generating the PDF. Preview your file at 100% zoom before uploading and check that the innermost text is well away from the page edge on both sides.