ISO 838 (4-Hole) vs. US 3-Hole
Comparing 2 standards across 9 specifications. 9 key differences identified.
The ISO 838 4-Hole extension (commonly known in Europe as the '888' format) specifies four holes spaced at three consecutive 80.0 mm intervals (80–80–80 mm, spanning 240.0 mm total) with standard 6.0 mm hole diameters. It is standard for heavy A4 4-ring presentation binders and archival document protectors to prevent page sagging.
The North American 3-Hole Standard is the ubiquitous paper punching system in the United States, Canada, and Mexico for 8.5 × 11-inch US Letter paper. Specifying three circular holes spaced exactly 4.25 inches (107.95 mm) apart (an 8.5-inch total span) with 5/16-inch (7.94 mm) hole diameters, it is the standard for 3-ring school and business binders.
Specification Comparison Table
9 Parameters| Parameter / Spec | ||
|---|---|---|
|
Hole Diameter
|
6.0 ± 0.5 mm | 5/16 in (7.94 mm) standard or 9/32 in (7.14 mm) |
|
Edge Distance to Hole Center
|
12.0 ± 1.0 mm | 0.375 to 0.50 in (9.5 to 12.7 mm) |
|
Primary Applications
|
4-ring A4 presentation binders, clear plastic sheet protectors, heavy catalog binders | School 3-ring binders (Avery, Wilson Jones), corporate training manuals, loose-leaf filler paper |
|
Hole Interval Geometry
|
Three 80 mm gaps: 80 mm – 80 mm – 80 mm (total outer span: 240.0 mm) | — |
|
Outer Hole Margin on A4
|
28.5 mm from top and bottom edges of an A4 sheet (297 mm length) | — |
|
Backwards Compatibility
|
Middle two holes match standard ISO 838 2-hole binders exactly | — |
|
Center-to-Center Hole Spacing
|
— | 4.25 in (107.95 mm) |
|
Total Outer Hole Span
|
— | 8.50 in (215.90 mm — from top hole center to bottom hole center) |
|
Top & Bottom Margins on US Letter
|
— | Exactly 1.25 in (31.75 mm) from sheet edge to outer hole centers |