The Imperial Paper Sizes includes over 30 different sizes, each with distinct dimensions and aspect ratios. Names like Foolscap came from the jester’s cap watermark used on paper in the 1400s. Crown paper featured a crown watermark, while Elephant paper bore an elephant design.

These sizes dominated British commerce, government, and printing from the 15th century until the 1980s. The UK officially adopted ISO 216 standards in 1959, but Foolscap paper remained in office use until the mid-1980s. Many Brits incorrectly called A4 paper “Foolscap” during this transition period.

Imperial paper measurements differ fundamentally from US standard sizes like Letter (8.5 × 11 inches) and Legal (8.5 × 14 inches). They also vary from ISO A-series dimensions, which maintain a consistent 1:√2 aspect ratio across all sizes.

Complete Imperial Paper Size Chart with Dimensions

Here’s the comprehensive imperial sheet sizes chart with all these measurements (Mm, Cm, M, Inches, Pt, Pc, Px @300ppi):

Understanding Folio, Quarto & Octavo Paper Terminology

Folio, Quarto, and Octavo refer to folding methods used in bookbinding, not standalone paper sizes. A folio means the sheet is folded once, creating 2 leaves (4 pages). Quarto means folded twice for 4 leaves (8 pages), and Octavo means folded three times for 8 leaves (16 pages).

For example, Royal paper measures 20 × 25 inches. When folded into Royal Octavo format, each resulting page measures approximately 6.25 × 10 inches. This naming system was crucial for printers and bookbinders determining page counts and book dimensions.

Imperial Paper Sizes vs US Standard Paper Sizes

US Letter paper (8.5 × 11 inches) doesn’t match any imperial format exactly. The closest imperial equivalent is Quarto at 9 × 11 inches, slightly wider than Letter size.

US Legal paper (8.5 × 14 inches) is taller than most small imperial formats. Foolscap (13.5 × 17 inches) is the nearest match but considerably wider. US Tabloid/Ledger (11 × 17 inches) falls between Crown (15 × 20 inches) and Medium (18.5 × 23 inches).

The key difference lies in aspect ratios. Imperial sizes have varying ratios from 1:1.18 to 1:1.71, while US formats maintain simpler proportions. This inconsistency made scaling difficult, which contributed to imperial formats becoming obsolete.

ISO A4 paper (210 × 297 mm or 8.27 × 11.69 inches) is narrower and taller than US Letter but doesn’t match Foolscap Folio (8 × 13 inches) either. Americans rarely use A4, preferring Letter size for standard documents.

When Americans Encounter Imperial Paper Sizes Today

Americans most commonly see imperial paper formats in historical archives and genealogical records. British colonial documents, immigration papers, and 18th-19th century correspondence often use Crown, Foolscap, or Post sizes.

Art collectors and museums frequently handle imperial-sized prints and drawings. Many vintage British lithographs, etchings, and watercolors were created on Royal, Imperial, or Elephant paper stock.

Rare book dealers must understand imperial dimensions. Books printed before 1960 in Britain used Demy Octavo, Crown Quarto, or Royal Octavo formats. Modern reprints of classic texts sometimes maintain these original dimensions.

International business documents occasionally arrive in imperial formats from UK-based companies maintaining legacy systems. Some British architectural firms still reference Antiquarian or Atlas sizes for large-format technical drawings, though this practice is declining.

FAQ’s (Imperial Paper Sizes)

What size is imperial paper?

Imperial paper refers to multiple British paper formats, not a single size. The format named “Imperial” specifically measures 22 × 30 inches (559 × 762 mm). Over 30 different imperial paper sizes exist, ranging from Monarch at 7.2 × 10.5 inches to Emperor at 48 × 72 inches.

What is 24×36 paper called?

24×36 inch paper doesn’t correspond to a standard imperial size. The closest imperial format is Broadsheet at 18 × 24 inches or Imperial at 22 × 30 inches. In modern terms, 24×36 inches matches ARCH D in the architectural series, commonly called “D-size” in engineering drawings.

Is A1 or A2 bigger?

A1 paper is bigger than A2. A1 measures 594 × 841 mm (23.4 × 33.1 inches), while A2 measures 420 × 594 mm (16.5 × 23.4 inches). Each number decrease in the ISO A-series doubles the paper area. A0 is largest, followed by A1, A2, A3, A4, and so on.

Is A4 the same as 8.5 x11?

No, A4 and Letter (8.5 × 11 inches) are different sizes. A4 measures 210 × 297 mm (8.27 × 11.69 inches), making it narrower and slightly taller than US Letter paper. This 0.23-inch width difference causes formatting issues when converting documents between US and international standards.

What size is a full imperial sheet?

A “full imperial sheet” traditionally means the uncut, unfolded paper before trimming. The specific size depends on which imperial format you’re referencing.

Imperial format itself measures 22 × 30 inches as a full sheet. Royal is 20 × 25 inches, Crown is 15 × 20 inches, and Foolscap is 13.25 × 16.5 inches uncut (different from the cut Foolscap Folio at 8 × 13 inches).

Conclusion

Imperial paper sizes represent British printing heritage before ISO standardization. These formats—from tiny Monarch to massive Emperor—featured unique dimensions and memorable names like Foolscap, Crown, and Royal.

Americans encounter imperial sizes in archives, rare books, and British documents. Understanding these measurements helps navigate historical records and international materials effectively.