Manufacturer · Fashion & Home Accessories
Zip sizes are indicated by numbers – № 3, № 5, № 8, № 10, etc. The number roughly corresponds to the width of the closed chain (teeth) in millimetres. The larger the number, the bigger the teeth, the wider the tape, and the higher the load the zip can handle.
What the number means – zip sizes in brief
The number is not the length. A size 5 zip can be 15 cm or 80 cm long – the number only describes the “gauge” of the chain. Therefore, when ordering, you always specify two separate values: size and length. You also add the zip type (metal, coil, moulded, invisible) and the opening style (separating, non-separating, two-way).
This system is historically linked to the chain width and is not an exact measure. Different manufacturers have slight variations – one size 5 may be 5.0 mm, another 5.6 mm. That is why the slider must always match the same size and type as the chain; otherwise, it will not engage properly.
Zip size chart
| Size | Approx. Chain Width | Product Weight | Typical Applications |
|---|---|---|---|
| № 2–3 | 3–4 mm | Light | Dresses, blouses, skirts, pockets, lingerie, small pouches |
| № 4–5 | 5–6 mm | Medium | Trousers, jeans, sweatshirts, light jackets, bags |
| № 6–7 | 6–7 mm | Medium to heavy | Jackets, vests, workwear |
| № 8 | 8 mm | Heavy | Winter jackets, parkas, backpacks, duffel bags |
| № 10 and above | 10+ mm | Very heavy | Luggage, tents, awnings, technical products |
How to identify a zip size
- Close the zip.
- Use a caliper or ruler to measure the width of the engaged teeth – from the outer edge of the left row to the outer edge of the right row, excluding the tape.
- Round to the nearest whole number – this is the size.
- Check the slider: it often has a stamped number and manufacturer code on the back, e.g. “5” or “8”.
If the zip is from an old product, the slider number is the most reliable guide – provided the slider is original.
Sizes by zip type
Coil zips
Coil zips come in the widest range – from very fine № 2 and № 3 for lingerie and dresses to № 8 and № 10 for sleeping bags, tents, and luggage. Invisible zips are usually size № 3, sometimes № 4 or № 5 for heavier fabrics.
Metal zips
Metal zips most commonly use № 4 and № 5 (jeans, trousers, bags) and № 8 (jackets, leather goods). The size here strongly affects the look – larger metal teeth are a prominent detail.
Moulded plastic zips
Moulded zips typically start from № 3 and № 5 for sweatshirts and children’s jackets, while № 8 and № 10 are standard for winter, workwear, and outdoor clothing. The robust plastic teeth handle stress and cold well.
How to choose the right size
Choosing a size balances three factors: load, fabric, and appearance.
- Load: the more the zip is stretched (tight jacket, backpack, full bag), the larger the size needed.
- Fabric thickness: size 8 on fine chiffon will weigh down and pucker the seam; size 3 on thick fleece or leather will look lost and wear out quickly.
- Appearance: jackets often use a larger size not only for strength but as a design accent.
- Collection consistency: jacket pockets usually have a smaller size than the central zip – e.g. size 5 for pockets and size 8 for the front.
Example: zip sizes for one jacket
Consider a winter jacket with medium volume. The central zip is usually a separating or two-way № 8 – moulded or coil. The pockets use non-separating № 5 zips, and the inner pocket uses № 3. If the jacket has a detachable hood, it attaches with a separate separating № 5 zip. Thus, one model has three sizes, each chosen for its load. A similar logic applies to backpacks – the main compartment with № 8 or № 10, smaller pockets with № 5.
Size, slider, and compatibility
The slider is made exactly for the width and profile of the chain. A size 5 slider for a coil zip will not work on a metal size 5 zip because the tooth profiles differ. When ordering replacement sliders, specify both the zip type and size. If you plan sliders with logos, the handle shape may be common across sizes, but the slider body differs.
Common mistakes
- Confusing size with length – “zip 5” is not 5 cm long.
- Ordering a slider by size only, without specifying zip type.
- Choosing too small a size for a separating zip on a winter jacket – the chain opens at the bottom when sitting.
- Mixing sizes in a set (jacket and trousers) that should visually match.
You can browse all sizes and types in the zips category, and for heavy jackets and outdoor products – in moulded zips and metal zips.
Polkom – zip size consultation
Polkom is a Bulgarian manufacturer of accessories for fashion, furniture, footwear, and bags with over 30 years of experience and more than 10,000 items. If you are unsure which size to choose, send us a description of your product, fabric, or sample – we will recommend the right size and send a sample. Contact us via the inquiry page.
