The safe zone is where your important design elements should go — away from areas that might be trimmed or shift slightly during binding.
Keep all critical text, logos, and images at least 0.25" away from the trim edges.
For the spine area, leave even more space. As your page count increases, so does the glue area along the spine. For example:
On a thin 32-page book, the glue area is minimal
On an 88-page book (a common size), the glue extends deeper — and the first 0.25" to 0.375" on both sides of the spine may become hard to read
Avoid placing anything important within 0.25" to 0.375" of the inside edge (spine side) of each page.
This is especially important when you're using elements like text or faces near the spine — these can end up looking pinched or lost in the glue area.
Tip: Always test your layout by imagining the book opened. If you can’t clearly see an element near the spine, move it out.** Always test your layout by imagining the book opened. If you can’t read or see an element near the spine clearly, move it out.