Size is the most basic zipper parameter, yet many people know only that "size 5 is the most common" without understanding the actual differences between sizes. The comparison below covers teeth width, typical applications, and pull strength reference values.
1. Size and teeth width
- Size 2: teeth width about 3.5–4 mm, for lightweight underwear, dresses, and small pockets
- Size 3: about 4.5–5 mm, shirts, dresses, lightweight jackets
- Size 4: about 5–5.5 mm, between sizes 3 and 5, for medium-weight fabrics
- Size 5: about 6–7 mm, the most versatile, jackets, down jackets, bag interior pockets
- Size 8: about 7.5–8.5 mm, heavy jackets, workwear, medium bags
- Size 10: about 9–10 mm, large bags, outdoor equipment
- Size 12: about 10.5–12 mm, industrial covers, tents, heavy-duty bags
- Size 15: above 12 mm, special equipment, essentially never used in apparel
Note: teeth width varies between manufacturers and materials (nylon/resin/metal), so cross-supplier substitution must be based on physical measurement, not on size number alone.
2. Pull strength reference
Flat pull strength rises with size, and at the same size metal ≥ resin ≥ nylon. Typical reference values: size 3 nylon 300–450 N, size 5 500–700 N, size 8 700–900 N, size 10 and above can exceed 1000 N. Actual values are subject to the test report; ranges must not be used as acceptance criteria.
3. Selection boundaries
- The thicker the fabric, the more fill, and the longer the placket, the more you should go up one size
- Fitted or lightweight styles should prioritize small sizes to avoid fabric push and bulk
- Load-bearing areas (bag shoulder-strap compartments, workwear plackets) must not be downsized to save cost
- Invisible zippers usually come only in sizes 3 and 5; do not apply the sizing logic of standard zippers
YCC Donglong can provide physical samples of each size and measured teeth width data; when changing suppliers, compare physical samples before fixing the specification.