Quick Answer
Spiral binding sizes are defined by four measurements: coil diameter, pitch, coil length, and trim size. Match the coil’s inside diameter to the finished sheet stack, include covers and dividers in that measurement, and confirm the pitch and cut length against the binding edge. Keep a signed sample and record all four measurements in the purchase order so repeat runs stay consistent. JIANXI supports buyers with custom trim sizes, paper options, sample approval, and coil-notebook production.
This guide shows purchasing managers and distributors how to choose spiral binding sizes using coil diameter, page count, format, sample checks, and purchase-order details.
What Do “Spiral Binding Sizes” Actually Measure?
Spiral binding sizes can refer to four separate specifications:
- Coil diameter: the inside measurement of the coil, which controls capacity.
- Coil length: the cut length along the binding edge.
- Pitch: the number of punched holes per inch.
- Trim size: the finished notebook size, such as A5 or B5.
The term spiral binding coil sizes usually means the diameter and pitch combinations available for a project. An A5 notebook does not automatically use a “medium” coil; its paper, covers, and sheet count determine the diameter. Ask for all four details in every quote. Our guide to notebook binding methods shows how coil binding compares with other finishing options.
What Coil Diameter Fits My Page Count?
Size by sheets, not pages. One sheet has two sides, so a 60-sheet notebook contains 120 pages when printed both sides. The coil must hold the full stack, including covers and dividers.
| Coil inside diameter | Typical sheet capacity* |
|---|---|
| 6 mm / 1/4 in | 20–40 sheets |
| 8 mm / 5/16 in | 35–60 sheets |
| 10 mm / 3/8 in | 50–80 sheets |
| 11 mm / 7/16 in | 65–100 sheets |
| 13 mm / 1/2 in | 80–120 sheets |
| 16 mm / 5/8 in | 100–150 sheets |
| 19 mm / 3/4 in | 130–190 sheets |
| 22 mm / 7/8 in | 170–230 sheets |
| 25 mm / 1 in | 200–270 sheets |
| 32 mm / 1-1/4 in | 260–330 sheets |
| 38 mm / 1-1/2 in | 320–390 sheets |
| 51 mm / 2 in | 390–450 sheets |
*Planning ranges only. Confirm the final size with a physical sample.
Use this chart as a starting point. At the same sheet count, 100 gsm paper takes more space than 70 gsm. Our GSM paper guide for notebooks explains why.
How to Choose Coil Binding Size for a Notebook
Use the same four checks for every SKU:
- Count the finished sheets. Include the title page, dividers, pockets, and inserts.
- Measure the compressed stack. Put the complete book block under light pressure and use the largest thickness reading.
- Allow working clearance. The pages should turn freely without shifting loosely. A coil that exactly matches the stack may feel tight.
- Match the pitch and cut length. The punch, coil, and binding edge must share the same pitch. The coil should cover the edge with a short, even overhang at both ends.
For a new product, approve a sample made with the final paper, cover, and punch. Plain-paper tests do not show how a laminated cover or tabbed divider will behave.
Why Does Coil Pitch Matter as Much as Diameter?
Pitch is the spacing of punched holes, usually stated as holes per inch. A 4:1 pitch has four holes per inch; a 5:1 pitch has five. The pitch affects appearance, minimum coil diameter, and compatibility with the punch or finishing line.
Two coils can share a diameter but use different pitches, and they are not interchangeable. Put the pitch in the purchase order and keep it consistent across repeat orders. See comb binding vs. spiral binding for a comparison of common styles.
Understanding the various notebook binding methods helps you select the structure, durability, and designs that best fit your project.
Read ArticleWhich Coil Size Fits Your Notebook Format?
Notebook format sets the binding edge, but not the diameter by itself. A6, A5, B5, A4, and Letter books can each use several coil sizes depending on thickness.
- A6: Check that the coil does not catch in a pocket or retail display.
- A5: A common format for journals, planners, and stationery programs.
- B5: Confirm the exact trim size; B5 dimensions can vary between suppliers.
- A4 and Letter: Longer coils and heavier books need careful sample testing.
Our guide to different notebook sizes explains how trim dimensions affect paper use, packing, and retail presentation.
The A5 Coil Body is a useful reference: 140 × 207 mm trim, 60 sheets of 70 gsm yellow paper, a 350 gsm white-card cover with matte film, and a black double coil. It shows how those choices work together.
Should You Choose a Single or Double Coil?
A single coil is one continuous spiral. A double coil uses two interlocked strands, giving a fuller look and a different feel when opened. Review the choice with diameter and pitch. Our article on what a double spiral notebook is explains the construction.
How Do You Check Coil Sizing in a Production Sample?
Test the sample as both a buyer and a user:
- Pages turn individually without tearing.
- The book opens comfortably and does not pull back sharply.
- Coil ends are clean, safe, and even.
- The coil does not crush the cover or create a hard ridge.
- Hole pattern, trim size, sheet count, and packing match the approved brief.
Record the approved diameter, pitch, color, and length on the sample card so repeat orders cannot drift. JIANXI’s quality process covers material, in-process, and finished-product checks.
Which Coil Specification Belongs in a Purchase Order?
Include the trim size and orientation, sheet count, paper weight and type, cover material and finish, coil diameter, pitch, coil color and construction, cut length, punch-hole size and margin, plus packaging and carton quantity.
Add a signed or photographed golden sample. “A5, 80 sheets, black coil” leaves cover weight, paper thickness, pitch, and coil length open to interpretation.
How Should You Compare Coil-Bound Notebook Quotes?
Compare total supply cost, not unit price. A lower quote may use a thinner cover, fewer sheets, or looser packing. Ask every supplier to quote the same bill of materials and sample standard, then compare MOQ, sampling, lead time, packaging, carton strength, and defect handling.
Why Can JIANXI Help With Coil Notebook Sourcing?
JIANXI supports OEM and ODM notebook programs for buyers who need a practical balance of specification, sampling, and production consistency. We work with A4, A5, B5, and custom trim sizes, portrait or landscape orientation, different paper stocks, and a range of cover and binding options.
Custom orders can start at 500 pieces. Sampling commonly takes 5–7 days, and bulk production commonly runs 10–20 working days after approval, depending on specification and volume. Confirm the schedule with your quotation.
A useful brief includes trim size, sheet count, paper weight, cover idea, coil color, pitch if known, target quantity, and delivery market. If the coil size is open, we can review the page count and recommend a sample route before artwork is finalized.
Frequently Asked Questions
How do I know what coil size to use?
Measure the finished stack, including covers and dividers, then choose a coil with a small working clearance. Confirm it with a sample using the final paper and cover.
What is a common coil binding size for a notebook?
For many notebooks with 50–120 sheets, 3/8 inch to 5/8 inch coils are common. Heavy paper, thick covers, or dividers can require a larger diameter.
Is coil diameter the same as notebook thickness?
No. Coil diameter measures the inside of the coil; notebook thickness measures the stack. The coil needs enough clearance for pages to turn.
Can the same coil be used for A5 and B5 notebooks?
Only when binding edge, sheet stack, and pitch match. A5 and B5 usually need different coil lengths, and page counts may call for different diameters.
Final Checklist and Next Step
To choose spiral binding sizes, measure the finished stack, select a diameter with working clearance, match the pitch to the punch, and confirm coil length against the binding edge. Then prove the choice with a sample and record it in the purchase order.
For a retail, corporate, or private-label coil notebook, send your trim size, page count, paper preference, and target quantity to JIANXI. We can turn those inputs into a practical coil specification and a sample for approval.
