For a two-sided book in Word, use mirror margins so the binding edge alternates between left and right pages, then add only the gutter allowance specified for your chosen print format. Mirror margins set the inside and outside edges; they do not tell you how much room a particular binding needs. Confirm trim size and binding requirements with the printer before changing the layout.
1. Get the print specifications first
Ask for the finished trim width and height, recommended inside margin or binding allowance, safe area, bleed requirements for edge-to-edge artwork, and the requested PDF format. Record these values before adjusting the manuscript. Do not copy margins from a different book or assume that every binding needs the same gutter.
Keep the interior PDF in normal reader-page order unless the printer specifically requests an imposed file. Word’s Book Fold setting creates booklet-style print order for folding sheets; it is not the usual setting for submitting a standard book interior.
2. Save a copy and set mirror margins
- Save a versioned copy of your DOCX.
- Open Layout > Margins > Custom Margins in Word desktop.
- Under Multiple pages, choose Mirror margins.
- Enter the printer-approved values in Inside and Outside, then set Top and Bottom as required.
- Choose OK and inspect a pair of facing pages in Print Layout.
With mirror margins, the inside margin appears on the binding side of both pages: on the right side of a left-hand page and the left side of a right-hand page. The outside margin remains toward the fore edge. Word for the web preserves existing mirror margins but Microsoft says to use desktop Word to add them.
3. Add a gutter only when the specification calls for it
A gutter is extra space for binding so text is not hidden near the spine. In Layout > Margins > Custom Margins, enter the specified amount in the Gutter box. When mirror margins are selected, Word determines the gutter side automatically; a separate Gutter position control may be unavailable.
Do not guess a value from page count alone. Binding style, paper, trim, and production method affect the usable area. If the printer’s instructions give a minimum inside margin and a separate gutter, ask how they expect those values to combine before entering them.
4. Apply the change to the intended pages
Before you select OK, check the Apply to setting. If your manuscript has multiple sections, Word may apply a margin change only to the current section. For a book with one consistent interior layout, apply it to the whole document. For different front matter or appendices, confirm whether those sections should share the same page geometry.
If different sections should have different margins, inspect section breaks with Home > Show/Hide ¶. Avoid adding breaks simply to fix one page; extra sections can also affect headers, footers, page numbering, columns, and orientation.
5. Check the facing pages and binding area
- Switch to Print Layout and show multiple pages side by side.
- Check an odd-numbered and even-numbered page: the wider inside margin should alternate toward the spine.
- Inspect text, footnotes, page numbers, captions, and table edges near the inside margin.
- Review chapter openings and pages with dense diagrams or equations; important content should remain within the printer’s safe area.
- Check the outside edge too so the text block remains balanced and page numbers are not crowded.
If the inside margin appears on the same side in every page, confirm that Multiple pages is set to Mirror margins and that the document is displayed as facing pages. Do not compensate by dragging paragraphs or inserting blank spaces.
6. Export the interior PDF without imposing pages
- Export a fresh PDF after the margin changes.
- Check the PDF’s page dimensions against the agreed trim size. Printer specifications determine the correct output size and whether bleed is needed.
- Open the file in a PDF reader and inspect the first, middle, and last pages, plus representative facing-page spreads.
- Check that all pages remain in reader order and that no spread has been manually split or rearranged.
- After any final layout correction, export again and verify the new PDF rather than relying on an earlier export.
Quick preflight checklist
- Trim size and binding requirements came from the selected printer.
- Mirror margins are enabled for the intended sections.
- Inside, outside, and gutter values follow the actual specification.
- Facing pages show the inside margin alternating correctly.
- Text and page elements stay within the safe area.
- The exported PDF matches the required page size and remains in reader order.
Request a print-file check
When your interior PDF is ready, submit it for a free file check. Include the trim size, page count, binding type, quantity, and the printer’s margin or gutter instructions.
Official Microsoft references
- Microsoft Support: set mirror margins for facing pages.
- Microsoft Support: set gutter margins.
- Microsoft Support: create a booklet or book in Word, including the distinction of Book Fold layout.