Binder Rings vs. ISO 838 (4-Hole)
Comparing 2 standards across 13 specifications. 13 key differences identified.
Binder Ring Mechanisms (manufactured in Round Ring, Straight D-Ring, and Slanted Angle D-Ring profiles) are mechanical document holding spines sized by internal ring diameter from 0.5 inches (13 mm / 100 sheets) up to 4.0 inches (102 mm / 900 sheets). D-rings hold up to 25% more pages than round rings of the same nominal size by stacking pages against a flat vertical spine.
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.
Specification Comparison Table
13 Parameters| Parameter / Spec | ||
|---|---|---|
|
0.5-inch Ring Capacity (13 mm)
|
Approx. 100 to 125 sheets (20 lb bond paper) | — |
|
1.0-inch Ring Capacity (25 mm)
|
Round Ring: 175 sheets | D-Ring: 220 to 250 sheets (+25% capacity) | — |
|
1.5-inch Ring Capacity (38 mm)
|
Round Ring: 275 sheets | D-Ring: 350 to 400 sheets | — |
|
2.0-inch Ring Capacity (51 mm)
|
Round Ring: 375 sheets | D-Ring: 480 to 540 sheets | — |
|
3.0-inch Ring Capacity (76 mm)
|
Round Ring: 450 sheets | D-Ring: 650 to 720 sheets | — |
|
4.0-inch Ring Capacity (102 mm)
|
D-Ring / Angle D-Ring only: 850 to 950 sheets (heavy-duty locking booster) | — |
|
Mounting Location
|
Round rings mount to spine; D-rings mount to back cover (enabling flat page opening) | — |
|
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 |