Spine width for a 300-page A5 book

A 300-page A5 paperback has the estimated spine width and full cover spread shown below. Use this for early planning only, then check the printer's A5 template before export.

Why A5 needs a separate cover spread

A5 is close to some inch-based trade paperback sizes, but it is not the same document size. Use the A5 trim dimensions directly rather than adapting a 5 x 8 or 6 x 9 cover by eye.

• Use 148 x 210 mm for the trim panels when that is the printer's A5 size.
• Keep bleed in the same unit as the cover document.
• Compare the final spread against the printer's A5 template.

Metric workflow checks

If the interior and printer template are metric, keep the cover setup in millimetres until final export. Converting back and forth can introduce rounding differences.

• Record spine width in millimetres.
• Use millimetre artboard dimensions for the full spread.
• Only convert to inches if a supplier specifically asks for it.

Example inputs used

• Page count: 300
• Paper thickness per page: 0.095
• Trim width: 148
• Trim height: 210
• Bleed: 3

These are starting values for this example. Measure or confirm your own figures, then open them in the book spine width calculator.

Assumptions and limits

• Uses a typical paper thickness of 0.095 mm per page.
• Trim size A5 (148 x 210 mm) with 3 mm bleed.
• Printer-specific A5 templates can differ in bleed and safe areas.

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