WHAT SIZES OF BINDING COIL ARE THERE?
| Size (mm) | Diameter (in) | Number of Sheets* | Document Thickness |
| 6 | 1/4" | 30 | 3/16" |
| 7 | 9/32" | 35 | 7/32" |
| 8 | 5/16" | 45 | 1/4" |
| 9 | 11/32" | 55 | 9/32" |
| 10 | 3/8" | 68 | 5/16" |
| 11 | 7/16" | 75 | 11/32" |
| 12 | 15/32" | 85 | 3/8" |
| 13 | 1/2" | 95 | 13/32" |
| 14 | 9/16" | 108 | 7/16" | 16 | 5/8" | 125 | 1/2" |
| 18 | 11/16" | 135 | 9/16" |
| 20 | 3/4" | 155 | 5/8" |
| 22 | 7/8" | 175 | 11/16" | 25 | 1" | 205 | 7/8" | 28 | 1-1/8" | 215 | 15/16" | 30 | 1-3/16" | 235 | 1" | 32 | 1-1/4" | 250 | 1-1/16" | 35 | 1-3/8" | 265 | 1-3/16" | 38 | 1-1/2" | 280 | 1-1/4" | 40 | 1-9/16" | 300 | 1-3/8" | 45 | 1-3/4" | 350 | 1-1/2" | 50 | 2" | 390 | 1-3/4" |
*The paper capacities shown in the table are approximate numbers of 20# sheets and for an exact fit, you need to measure your finished document and use the sizes under document thickness. Include your covers while measuring. Coil binding is one of the more popular methods of binding today. Properties of coil binders are that pages turn easily, the book will lay flat and it's very durable with excellent crush resistance.
4:1 Pitch Hole Pattern
The most common hole pattern with coil binding is a 4:1 pitch hole pattern, 6mm overseas. This means that there are 4 holes per inch on the edge of the document. Usually the holes will be either round or oval shaped and depending on the size and spacing of the hole pattern, there will be 43 or 44 holes on an eleven inch binding edge. With 4:1 pitch spiral coil being available in sizes ranging from 56mm up to 50mm in diameter, you can bind documents that are up to two inches thick.
5:1 Pitch Hole Pattern
Some printers and binders prefer, though, a 5:1 pitch coil (5mm overseas.) The 5:1 pitch coil is more tightly wound and provides a neat and tidy appearance. However, the tight spacing of the coil and smaller size of holes that this pattern uses limits the size of spines available. Five to one pitch coil are available in diameters ranging from 6mm up to 25 mm, so documents larger than one inch thick can't be bound using this hole pattern. This pattern is not as common as the four to one pitch coil.
3:1 Pitch Hole Pattern
The 3:1 pitch spiral coil is less common than the 5:1 and the 4:1 pitch coils. It is designed to be used with the hole pattern used in Wire Binding or with GBC Proclick. Three to one is slightly easier to use with large diameter books since there are less holes to insert the coil through. The coils supplied for this type range from 6 mm up to 50 mm.
2.5:1 Pitch Hole Pattern
The 2.5:1 pitch coil, also known as a 0.400 pitch coil, is used with a hole pattern that has 2.5 holes per inch. This type of spiral coil uses a larger filament diameter and is specifically designed for binding thick documents. Since the spirals in this pitch pattern are available in diameters ranging from 20mm to 56mm, the 2.5:1 pitch coil can be used to bind documents that are thicker than any of the other pitches of spiral coil.