# item.guide
Side-by-Side Comparison Book & Publishing Formats

Duodecimo vs. Mass Market Paperback

Comparing 2 standards across 12 specifications. 12 key differences identified.

Comparing:
Duodecimo
Mass Market Paperback

A Duodecimo (abbreviated 12mo or 12°) is a classical pocket book format created by folding a printer's sheet into 12 leaves (24 printed pages). Measuring approximately 4.75 × 7.5 inches (120 × 190 mm) or 5.0 × 7.75 inches, it was the historical ancestor of the modern paperback, widely used for personal devotional books, poetry collections, and traveler guides.

View full Duodecimo spec sheet →

A Mass Market Paperback (also known as a Pocket Book / Rack-Size Novel) is a standardized commercial book publishing format measuring 4.25 × 6.875 inches (108 × 175 mm). Engineered for high-volume rotary letterpress/web offset printing on groundwood pulp paper, it is designed to fit spinning wire display racks in airports, supermarkets, and drugstores.

View full Mass Market Paperback spec sheet →

Specification Comparison Table

12 Parameters
Parameter / Spec
Folding Structure
Complex combination fold (often folding in thirds then quarters) —
Leaf and Page Yield
12 leaves (24 printed pages per sheet) —
Typical Dimensions
Approx. 4.75 × 7.50 inches to 5.0 × 7.75 inches (120 × 190 mm to 127 × 197 mm) —
Historical Significance
Aldine Press Renaissance pocket classics (Aldus Manutius, Venice, 1501) —
Modern Equivalent
B-format paperbacks (5.1 × 7.8 in / 129 × 198 mm UK standard) —
Width × Height (Imperial)
— 4.25 × 6.875 in
Width × Height (Metric)
— 108 × 175 mm
Paper Type
— High-bulk mechanical groundwood pulp paper (uncoated, prone to yellowing)
Binding Style
— Perfect Binding (cold EVA or hot PUR adhesive along trimmed spine)
Distribution Channels
— Wire revolving racks in grocery stores, airport kiosks, newsstands
Strip-Cover Returns Policy
— Unsold copies are 'stripped' (cover torn off for credit; body pulped)
Primary Genres
— Thriller novels, romance, science fiction, crime paperbacks