ISO 838 (4-Hole)
Binders & Hole Punching · 6 specs
Direct Answer
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.
Source: DIN 821-2 / ISO 838 Extension Specifications · Last reviewed Aug 28, 2026
Specs
| 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) |
| Hole Diameter | 6.0 ± 0.5 mm |
| Edge Distance to Hole Center | 12.0 ± 1.0 mm |
| Backwards Compatibility | Middle two holes match standard ISO 838 2-hole binders exactly |
| Primary Applications | 4-ring A4 presentation binders, clear plastic sheet protectors, heavy catalog binders |
The Anti-Sag Advantage of 4 Rings
In 2-ring binders, heavy stacks of 80 gsm paper tend to sag downwards under gravity, placing high shear stress on the two hole margins and causing pages to tear out over time. Adding the two outer rings distributes the document weight evenly across the entire 240 mm spine span.