Calculator

The Calculator is a comprehensive tool within Momovu that helps book publishers and designers calculate spine widths and total document dimensions for their book covers and dustjackets based on page count and book format.

Features

The Calculator provides two main functions:

  1. Spine Width Calculation: Calculates the spine width for covers and dustjackets based on page count

  2. Document Dimensions Table: Displays total document sizes for all supported book formats

Accessing the Calculator

The Calculator can be accessed from the main menu:

  1. Open Momovu

  2. Go to Document → Calculator…

  3. Or use the keyboard shortcut: Ctrl+K

Using the Calculator

The calculator dialog provides a comprehensive interface with two main sections:

Spine Width Calculation

  1. Page Count Input: Pre-filled with your current document’s page count - For interior documents: Uses the total page count from the PDF - For covers/dustjackets: Uses the value from the Pages spinbox in the toolbar

  2. Document Type Selection: Choose between Cover or Dustjacket

  3. The spine width is calculated automatically as you change the inputs

Calculator dialog showing spine width and document dimensions

Document Dimensions Table

The lower section displays a table showing total document dimensions for all supported book formats:

  • Book Format: The name of the book format (e.g., A4, US Trade, Novella)

  • Trim Size: The single page trim size in millimeters

  • Total Document Size: The complete document dimensions including: - For covers: Front + back + spine + bleeds - For dustjackets: Front + back + spine + flaps + bleeds + fold safety margins

The table automatically updates when you: - Change the page count - Switch between Cover and Dustjacket modes

Production Details Table

The Production Details table provides all the production dimensions you need for book printing.

Displayed Dimensions:

The table shows different information based on your document type selection:

For Covers:

  • Barcode Area: The designated area for barcode placement

  • Bleed Area: The bleed extension beyond trim marks (6.35 mm)

  • Gutter Width (per page): Dynamic width added to the safety margin based on page count

  • Safety Margin: The margin area to keep important content away from edges

  • Spine Width: Dynamic calculation based on page count and selected formula

For Dustjackets:

  • Barcode Area: The designated area for barcode placement

  • Bleed Area: The bleed extension beyond trim marks (6.35 mm)

  • Flap Width: The width of each dustjacket flap (82.55 mm)

  • Fold Safety Margin: Safety margin at fold lines (6.35 mm)

  • Gutter Width (per page): Dynamic width added to the safety margin based on page count

  • Safety Margin: The margin area to keep important content away from edges

  • Spine Width: Dynamic calculation based on page count using lookup table

Key Features:

  • All values are displayed with proper units (mm) for precision

  • Values update automatically when you change the page count or document type

  • The Spine Width and Gutter Width are dynamically calculated based on your page count

  • The Gutter Width is added to the safety margin to provide adequate binding clearance

Note

The Production Details table helps ensure your design accounts for all necessary production requirements. The gutter width calculation is particularly important for thicker books, as it provides additional space near the spine to prevent content from being lost in the binding.

Supported Book Formats

The Calculator supports 12 standard book formats:

  • A4 (210 × 297 mm)

  • A4 Landscape (297 × 210 mm)

  • A5 (148 × 210 mm)

  • Digest (139.7 × 215.9 mm)

  • Executive (184.15 × 266.7 mm)

  • Novella (127 × 203.2 mm)

  • Pocket Book (107.95 × 174.625 mm)

  • Small Landscape (152.4 × 101.6 mm)

  • Small Square (127 × 127 mm)

  • US Letter (215.9 × 279.4 mm)

  • US Letter Landscape (279.4 × 215.9 mm)

  • US Trade (152.4 × 228.6 mm)

Calculation Formulas

The calculator uses printer-specific formulas that can be selected in File → Preferences → Formulas tab. The default formula is for Lulu, but Lightning Source formulas with various paper weights are also available.

Cover (Paperback)

  • Spine Width (Lulu - Default): (pages ÷ 17.48) + 1.524 mm

  • Spine Width (Lightning Source): Varies by paper weight selection

  • Total Width: (Trim Width × 2) + Spine Width + 6.35 mm

  • Total Height: Trim Height + 6.35 mm

Dustjacket (Hardcover)

  • Spine Width: Based on page count lookup table

  • Total Width: (Trim Width × 2) + Spine Width + 165.1 mm + 12.7 mm + 19.05 mm

  • Total Height: Trim Height + 12.7 mm + 6.35 mm

The dustjacket calculation includes: - Flap width: 82.55 mm (3.25 inches) on each side - Bleed: 6.35 mm (0.25 inches) - Fold safety margins: 6.35 mm at each fold line

Requirements and Limitations

  • Minimum pages for covers: 32 pages

  • Dustjacket page range: 24-800 pages (outside this range shows a warning)

  • Maximum page input: 999 pages

Examples

Cover Examples:

  • 100 pages = 7.245 mm spine width

  • 200 pages = 12.966 mm spine width

  • 500 pages = 30.128 mm spine width

Dustjacket Examples:

  • 100 pages = 13 mm spine width

  • 350 pages = 27 mm spine width

  • 424 pages = 32 mm spine width

Document Size Example (US Trade, 424 pages):

  • Cover: 337.53 × 234.95 mm

  • Dustjacket: 533.65 × 247.65 mm

Note

Different printers use different paper thicknesses and specifications. You can select your printer’s formula in File → Preferences → Formulas tab. The default calculations are based on Lulu’s specifications, but Lightning Source formulas with various paper weights are also available. Always verify final dimensions with your printer’s official calculation tools before production, as these formulas are approximations.