Book margins are not wasted space. They make reading easier, protect text from trimming and leave enough room for the spine. A layout that looks right on screen can feel uncomfortable when opened if its inside margin does not account for the binding.
The inside margin does not always need to equal the outside margin. It depends on the page size, number of sheets and how the book opens.
What are inside and outside margins?
On facing pages, the inside margin is next to the spine and the outside margin is next to the fore edge. Their physical position swaps between left- and right-hand pages.
Top and bottom margins
The top margin frames the beginning of the text area, while the bottom margin can provide room for page numbers or editorial elements. Both should relate to the type size, page format and density of the content.
What is the gutter or binding allowance?
Some applications provide an additional margin setting to compensate for space taken up by the binding. Do not confuse it with bleed, which extends beyond the trim line.
How page count and paper affect margins
A thick book with restricted opening may require a larger inside margin. No universal measurement in millimetres can be recommended without knowing the paper and construction.
Example margin layout
For a 150 × 210 mm page, an initial test might use a 20 mm inside margin, 15 mm outside, 17 mm top and 22 mm bottom. This is not a mandatory specification. Check it against the typeface, spine and a physical mock-up.
Example margin table for a 150 × 210 mm page
As a composition exercise, a 150 × 210 mm novel could start with the following values and then be adjusted after reviewing the text area, typography and a bound proof. These are neither statutory minimums nor measurements for every book.
| Margin | Example starting value | What to check |
|---|---|---|
| Inside | 20 mm | Book opening and loss of readability near the spine |
| Outside | 15 mm | Column width and reading comfort |
| Top | 17 mm | Titles, running heads and start of text |
| Bottom | 22 mm | Page numbers and visual balance |
To determine the usable text area, subtract the margins from the paper size. With these values, it would be 115 × 171 mm before selecting leading and type size. If a print platform specifies minimum margins according to page count, check those requirements too; they are not the same as an editorial design recommendation.
Setting up facing pages in InDesign
Create a facing-pages document, define inside and outside margins and apply consistent styles. If the binding changes, review the inside margin and every element close to the spine.
Setting mirror margins in Word
Word provides mirror-margin and gutter options in its page setup. Their exact location can vary by version; check the result in print layout view.
How to find problems when reviewing the PDF
- Check both left- and right-hand pages.
- Review headings close to the spine.
- Make sure notes and page numbers do not enter the trim area.
- Inspect pages containing full-bleed images.
- Print a full-size mock-up.
- Check how the bound book opens.
Margins and the gutter determine line length. Complete the layout by checking that type size and leading remain comfortable throughout the book.
Frequently asked questions
How wide should a book margin be?
It depends on the page format and binding.
Are bleed and margins the same?
No.
Should inside margins be larger?
They may need additional space depending on the spine and opening behaviour.
Do you need to print a book or catalogue? Send us the page count, dimensions, material and binding method.
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