In this article
What does the zipper size number mean?
A zipper size (Size 3, Size 5, Size 8…) follows the international size number: Size 5 = No. 5 = #5. It is a size class based on the width of the closed chain. Width grows with the number, but it does not equal millimetres exactly: Size 5 is usually 5-6 mm, while Size 10 can be 8.5-10 mm. Exact millimetres vary slightly and are confirmed on a sample.
Metal zipper sizes and typical uses
| Size | Typical use |
|---|---|
| Size 3 | Skirts, dresses and lightweight garments |
| Size 4.5 | Lightweight jeans and women's trousers |
| Size 5 | Standard jeans, jackets, coats, bags and leather goods, one of the most common sizes |
| Size 8 | Heavy jackets, bags, boots |
| Size 10 | Overcoats, workwear, outdoor gear, heavy-duty use |
Nylon (coil) zipper sizes
The same logic applies to nylon (coil) zippers. Size 3 suits dresses and lightweight garments, Size 5 jackets, bags and home textiles, Size 8 luggage and outdoor products, and Size 10 tarpaulins, large luggage and heavy tents. Lighter tents can use smaller sizes.
Four questions for choosing the right size
- How thick is the fabric? Heavy denim and leather need a larger size.
- How much stress will it take? For load-bearing products such as bags and boots, Size 8 and above is safer.
- Does the look matter? Large metal teeth (Sizes 8, 10) look bold and durable.
- Which end type? Closed-end for trousers and bags, open-end (separating) for jackets, two-way for long coats and bags.
What do size numbers measure in millimetres?
There is no exact conversion, but manufacturer and technical sources give a useful guide. Use these ranges as a starting point. The exact width is confirmed on a sample.
| Size | Approx. closed width | Class |
|---|---|---|
| Size 3 | 4-4.5 mm | Light |
| Size 5 | 5-6 mm | Medium |
| Size 8 | 7-9 mm | Medium-heavy |
| Size 10 | 8.5-10 mm | Heavy |
Why can widths differ slightly?
A size is a class covering a range, not a single measurement. Metal and molded zippers of the same number can differ slightly. Exact millimetres are confirmed on a sample.
Are larger zippers stronger?
Generally yes. Minimum strength values in standards rise with size class. Real performance also depends on the tape, tooth type, slider and production quality, so size alone is no guarantee of strength.
Is Size 5 the same as No. 5 and #5?
Yes. The size follows the international size number, so Size 5 = No. 5 = #5.
How do I identify the size of my zipper?
- Check the number on the back of the slider.
- Remember it may be a mould number.
- Close the zipper and measure across the teeth.
- Round to the nearest size and confirm with the manufacturer.
Not sure? Request a sample
MAK Zipper manufactures metal zippers in Sizes 3, 4, 4.5, 5, 8 and 10, and nylon zippers in Sizes 3, 5, 7, 8 and 10. We also produce molded zippers and zipper by the metre, and sell all slider and puller types in metal and plastic. Tell us about your product, we will pick the right size together and send you a sample.
Frequently asked questions
How wide is a Size 5 zipper?
It is usually 5-6 mm. Exact millimetres vary slightly and are confirmed on a sample.
Is a Size 10 zipper exactly 10 mm?
Not always. Some products are around 8.5 mm and others are closer to 10 mm.
Is the size written on the slider?
Often, but the figure does not always indicate the size. Measuring the teeth is safer.
What is the most common zipper size?
There is no definitive market data, but Size 5 is seen as one of the most common sizes.
