Manufacturer · Fashion & Home Accessories
Metal zip sizes: each size is indicated by a number – No. 3, No. 4, No. 5, No. 8, No. 10 and so on. The number roughly corresponds to the width of the closed chain in millimetres: the larger it is, the bigger and stronger the teeth. For pockets and light garments No. 3–4 is used, for jeans and jackets No. 4–5, and for winter jackets, bags and heavy products No. 8 and above.
What the number of a metal zip means
There is no single standard for all zip manufacturers, but in the industry the number (gauge) is used as a common language. It describes the size of the chain – the width of the closed teeth – not the length of the zip. So a "No. 5, 60 cm" zip means a No. 5 chain with a length of 60 cm. The two parameters are always given together when you order metal zips.
There are also intermediate sizes – for example No. 4.5, which some manufacturers offer specifically for jeans. Different brands may have small differences in the actual width for the same number, so when replacing an existing zip it is best to compare it with a sample.
Metal zip sizes – chart
| Number | Look | Typical use |
|---|---|---|
| No. 3 | Fine, discreet chain | Pockets, shirts, light trousers, purses, children's clothing |
| No. 4 | Delicate but stable | Women's jeans, skirts, trousers, small bags |
| No. 5 | Classic | Men's jeans, denim and transitional jackets, handbags |
| No. 6–7 | Pronounced | Jackets, workwear, heavier bags |
| No. 8 | Heavy | Winter and leather jackets, backpacks, holdalls |
| No. 10 | Very large | Heavy outerwear, suitcases, statement designs |
The chart is a guide. The final choice depends on the fabric, the weight of the product and the look you are after.
How to find out the size of an existing zip
If you are replacing a zip or want to repeat a style, the size is easy to determine:
- Check the back of the slider. Many manufacturers stamp the size number and chain type on the slider body.
- Measure the closed teeth. With a calliper or ruler measure the width of the chain across when the zip is closed. The result in millimetres is close to the number.
- Compare with a sample. The surest way is to send a piece of the zip or a photo next to a ruler to the supplier.
Bear in mind that the tape width does not determine the number. Two zips with the same chain can have tapes of different widths.
The size also determines the slider
A slider is made for a specific size and chain type. A slider for a No. 5 metal zip will not work on a No. 4 metal or a No. 5 nylon coil zip, even if it looks similar. When replacing or ordering spare sliders, always state:
- the chain type – metal, nylon coil or moulded plastic;
- the size number;
- the slider type – auto-lock, semi-automatic, non-locking, two-way.
How to choose a size according to the product
Clothing
The lighter and finer the fabric, the smaller the number chosen. A heavy zip on a thin fabric drags down, creates waves along the seam and is visible from afar. Conversely, a zip that is too small on a winter jacket wears out quickly and is hard to grip. For jeans the difference between No. 4 and No. 5 is mainly a matter of style and denim weight. On jeans the zip is always closed-end with an auto-lock slider, whatever the number.
Bags and accessories
For bags the size is determined by the load and the radius of the curves. A large number on a small pouch with a curved opening makes sewing and the movement of the slider difficult. For travel bags and backpacks, on the other hand, No. 5 may prove insufficient when the bag is full.
Look and style
Large No. 8 and No. 10 metal zips are often chosen deliberately as a design accent – on biker jackets, voluminous coats and accessories. In this case the size is part of the aesthetic, and the finish – antique, black nickel, gold – further emphasises the effect.
Common mistakes when choosing the size
- Choosing from a photo alone. In a photo No. 4 and No. 5 look almost the same; the difference only shows on the finished garment. Ask for a physical sample.
- The same number for the whole collection. A jacket and its pockets do not have to have the same number – a smaller zip on the pocket looks more proportionate.
- A large zip on a thin fabric. The weight of the chain pulls the seam and creates waves.
- Chain type omitted. "No. 5 zip" without specification could be metal, nylon coil or moulded – always state the type as well.
- Replacing only the slider with a "similar" one. If the number does not match, the zip will split again after a short time.
Good practice with a new style is to sew one or two samples with two neighbouring sizes and decide after the fitting. It takes a little time but saves corrections in series production.
Size and length – how to state them in the order
To avoid misunderstandings, describe the zip in this order: chain type, number, material and finish, construction, length, tape colour, slider type. For example: "metal zip, No. 5, antique brass, closed-end, 18 cm, navy tape, auto-lock slider". If you are not sure of the number, send a sample or photo – we will determine it.
Metal zips in all sizes from Polkom
Polkom supplies wholesale metal zips in sizes from fine to very large, in various lengths and finishes and with custom logo sliders. If you need a lighter alternative in the same size, take a look at nylon coil zips, and for the original brand YKK metal zips. Send an inquiry with the product and the quantity – we will recommend a size and prepare samples.
