While most of the world uses ISO 216 (A4, A3...), the United States, Canada, Mexico, and the Philippines follow a different paper-size system.
Origin of Letter Size
Letter (8.5 × 11 inches = 216 × 279 mm) descends from colonial-era American writing paper traditions. When typewriters and mass-produced stationery arrived, Letter was already the default.
ANSI Paper Sizes
In 1996, ANSI formalised a series of sizes under ANSI/ASME Y14.1:
- ANSI A — 8.5 × 11 in (Letter)
- ANSI B — 11 × 17 in (Tabloid)
- ANSI C — 17 × 22 in
- ANSI D — 22 × 34 in
- ANSI E — 34 × 44 in
Letter vs Legal vs Tabloid
- Letter — 8.5 × 11 in (everyday default)
- Legal — 8.5 × 14 in (3 in longer)
- Tabloid — 11 × 17 in (twice Letter area)
- Ledger — 17 × 11 in (Tabloid rotated)
Why the US Didn't Switch
Existing filing cabinets, binders, envelopes, and printer trays were all Letter-based. The cost of switching outweighed the benefits.