What is a slug?

In book design, a slug refers to an area outside the trim and bleed that contains non-printing information for the printer. This space is typically used for fold marks, crop marks, colour bars, or other registration details that help with accurate printing and finishing.

Key Points About Slugs:

• Not Part of the Final Book – The slug area is outside the page’s trim size and is removed during the final cutting process.
• Used for Production & Finishing – Printers use the slug to align pages, check colours, and ensure accurate folding and binding.
• Typically 5mm–10mm in Width – The slug is often set to 10mm on all sides, though the size can vary depending on the print specifications.

Difference Between Bleed and Slug:

• Bleed extends background artwork beyond the trim edge to prevent white gaps after cutting.
• Slug contains guides and information for the printer and is not meant to be part of the printed book.