Perfect-Bound Cover Spread Calculator

Method, formula and assumptions

Trimmed spread width = back panel + spine + front panel + both flaps. Add bleed only at the two outside edges. Spine center is bleed + left flap + back panel + half the spine.

Input definitions and supported units

• Trimmed panel width (mm): Measured or assumed numerical value, from 1 to 1000; must be positive.
• Trimmed panel height (mm): Measured or assumed numerical value, from 1 to 1000; must be positive.
• Approved spine width (mm): Measured or assumed numerical value, from 0 to 500; zero is supported where the stated method permits it.
• Flap width on each side (mm): Measured or assumed numerical value, from 0 to 500; zero is supported where the stated method permits it.
• Outer bleed on each edge (mm): Measured or assumed numerical value, from 0 to 100; zero is supported where the stated method permits it.

Worked example with answer

148 x 210 mm panels, 12 mm spine, no flaps and 3 mm bleed produce a 308 mm trimmed spread, 314 x 216 mm artwork and a spine center 157 mm from the artwork's left edge.

How to use the results

Internal panel boundaries are not extra bleed edges. Use an approved spine width, then mark the center from the full artwork edge.

Results retain full precision internally and display up to four decimal places. Very small nonzero results use scientific notation rather than appearing as zero. Check the labels before comparing values across units.

Limitations and references

Excludes hinge scoring, wraparound case binding, hinge gaps and printer-specific cover templates. A computed spread does not replace a production template.

The method is a self-contained arithmetic, geometric or explicitly stated mathematical model. There are no imported tariffs, empirical presets or equipment specifications; measured values and allowances must come from your own process.

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