Zipper Types and Sizes: Which Zip for Which Garment?

Zip parts and the five decisions that drive selection

A zip consists of two tapes carrying the teeth and a slider that interlocks them. The tape is generally polyester; other synthetic-fibre, vinyl and cotton tapes exist for particular uses (YKK Fastening Catalogue, January 2022). The interlocked teeth are called the chain. The part attached to the slider is the pull (Turkish: elcik); the parts at the top and bottom ends of the chain are the top stop and bottom stop. An open-end zip also has a box and pin at the bottom. In Turkey the slider is also called kürsör (Ankara University OpenCourseWare, zipper lecture note).

Zipper types by tooth

The tooth type decides how the zip looks and how it behaves in washing, pressing and under load. The YKK catalogue separates metal and moulded plastic zips (individual teeth) from coil zips (continuous teeth).

Metal zips

The YKK catalogue describes the metal zip as the oldest zip type, with teeth made of metals such as gold-coloured brass, aluminium and nickel. According to Coats, a metal zip normally has a polyester tape and brass teeth. The Ankara University lecture note says metal teeth withstand stone and acid washing, which is why they are preferred in jeans, leather garments and sportswear; the same note says the zip loses its function if a single tooth breaks.

Metal zips have two limits. YKK says aluminium-alloy zips are sensitive to moisture, friction and acidic or alkaline environments, so they are not suited to harsh processes such as jeans washing and re-dyeing. According to the problem-and-solution section of the same catalogue, the lubricant on metal teeth and metal dust from opening and closing can stain light-coloured or absorbent fabric. Nickel has its own section below.

Coil (spiral) zips

The teeth of a coil zip are formed as a coil from polyester or nylon monofilament. According to Coats, the coiled monofilament is sewn onto two polyester tapes; in YKK’s “woven-in” type the teeth are woven in together with the tape, and the zip is thinner than a standard coil zip. YKK describes the coil zip as the softest of the three zip types. According to the lecture note, its flat surface has no sharp edge to catch fabric yarn; it is light, narrow and flexible, so it can be used on any fabric weight.

There are special series for knitted and stretch fabrics. In YKK’s knit-tape series the tape is soft and flexible; it does not disturb the fabric properties on curved seams, prevents puckering and suits light, flexible fabric. In the elastic-tape series only the tape stretches (10% stretch); the chain does not stretch crosswise.

Moulded plastic zips (kemik)

The group called kemik fermuar in Turkey corresponds to what international catalogues call “moulded plastic” zips. YKK Türkiye offers this group under the name VISLON® (kemik) and says it is made by injecting polyacetal raw material onto the tape; VISLON is YKK’s trade name. Coats also describes the moulded plastic zip as a polyester tape with POM (polyacetal) teeth. According to YKK, it is lighter than a metal zip of the same size. The lecture note says moulded plastic zips are mostly used in sports outerwear and in the open-end type.

Polyacetal is sensitive to strong acids. YKK advises against cleaning the teeth by soaking them in bleach, and says to rinse with water immediately if they touch substances such as toilet cleaner or battery acid.

Invisible (concealed) zips

On an invisible zip the teeth stay behind the fabric when closed. YKK presents this series as the most suitable zip for skirts and dresses because it does not disturb the garment design, and makes it in sizes 2, 3 and 5. YKK’s warnings are:

• When closing, fasten the hook or button first and pull the slider straight along the teeth; pulling at an angle damages the teeth.
• Do not use it where fabric thickness changes.
• On a close-fitting dress the lower end of the teeth can scratch the skin; cover the area under the movable bottom stop with a fabric lining or patch.

Special series

Zips with a water-repellent finish and polyurethane lamination form a separate group (YKK AquaGuard). They are marketed as water-repellent; where a product must be watertight, ask the manufacturer for its test certificate and class. Manufacturers also offer anti-nickel options, series compatible with metal detectors, and zips printed with a customer name or logo (YKK Türkiye).

Zip types by end construction and slider

Independently of the teeth, zips are also classified by how their bottom and top ends finish.

According to the lecture note, closed-end zips suit places where one end of the seam stays closed, such as a skirt waist opening or a neck opening, while open-end zips suit jacket and coat fronts, where the seam is open at both start and end and the two halves of the garment must separate completely.

Slider and lock types

The slider is the moving part of the zip; its lock type affects self-opening and washing resistance.

• A non-lock slider has no locking mechanism and can open easily under strain (lecture note).
• An auto-lock slider is the type whose lock engages by itself when the pull is released.
• A semi-auto-lock slider locks when the pull is laid down. YKK’s jeans slider is of this type.
• On a pin-lock slider a projection in the slider head enters a lock slot (lecture note). In YKK’s problem-and-solution section, a pin-lock slider whose projection hurts in a pocket is listed as a complaint; an auto-lock or non-lock slider is suggested as the solution.

For washed products, YKK writes that the pull of an auto-lock slider can jam in the drum and break off, and that chemical residue on its cover can corrode the slider; for these processes it recommends the more durable semi-auto-lock jeans slider. According to Coats, the slider body is usually a zinc alloy; stamped brass sliders are used in jeans applications.

Turkish zip terms decoded

Quotations and tech packs from Turkish suppliers often use local trade words. This table maps the common ones to the English terms you should write in your own specification.

What does a zipper size number mean?

The zip size number is a size class based on the width of the interlocked teeth on a closed zip, in other words the chain width. The YKK catalogue classifies zips by chain width and uses the six classes of the Japanese standard JIS S 3015. The table below shows how one manufacturer’s product codes are distributed across these classes.

Source: YKK Fastening Catalogue, January 2022, “Strength Standards”. For the ultra heavy class the catalogue gives only the value “12.0”; “and above” is inferred from the end of the previous band. The class names above are descriptive labels. Product sizes are YKK’s standard series; another manufacturer’s zip with the same size number may fall in a different band.

Three conclusions follow from the table:

1. A size number is not millimetres. “Size 5 = 5 mm” is a common shortcut, but in the table a size 5 coil zip sits in the 5.5–7.0 mm band. The lecture note also gives tooth widths for metal zips of 4.30–4.40 mm for Tip 3 and 5.80–6.00 mm for Tip 5.
2. The minimum strength rises with the class. In the JIS classes, the expected minimum crosswise chain strength for a zip with individual teeth or chemical-fibre tape is 150 N in the lightest class and 690 N in the heaviest. YKK adds that strength also varies from item to item within the same JIS class.
3. Not every size exists in every type. In the table, size 15 appears only in the moulded plastic group, size 7 only in metal and size 4.5 only in coil.

Turkish “tip” numbers versus international size numbers

In Turkey, nylon (coil) zips are often sold by “tip” number, and these numbers may not follow the same scale as international sizes. In the lecture note’s table, nylon zips are listed with both a “tip” and a “no”, and the two are not the same: for example, “Tip 5 (no 3, corded)” is given with a tooth width of 4.00–4.20 mm. Some tip numbers appear on more than one row of the table, so read the match from the manufacturer’s own table rather than row by row. On the pocket-zip page of a zip seller in Turkey, Tip 7 is given a tooth width of 4.9 mm and is described as having thicker teeth than the Tip 5 used for trousers and skirts.

So a “Tip 5 trouser zip” and the size 5 coil zip in the YKK catalogue (5.5–7.0 mm band) may not be the same product. When ordering, do not write only “size 5”: state the tooth type, the tooth width in millimetres and, where possible, the manufacturer’s chain code.

Working out the size of a zip you already have

Close the zip and measure the width of the teeth from outer edge to outer edge with a calliper, in millimetres. Do not take the result as the size number; match it to the band in the manufacturer’s table. If you will reorder the same item, send the zip itself as a sample.

Which zip for which product?

A seller’s guide gives a general rule: the longer and heavier the product, the thicker the teeth should be (E-Fermuar guide). The table below is a starting point. The size suggestions rest on product families and the series ranges in one manufacturer’s catalogue; they are not a standard matching table. Make the final decision on a sample, with your fabric weight, style and washing conditions; for fabric weight classes, see fabric weight by product.

How to measure zipper length, and what tolerance to allow

Length is measured with the zip closed. According to YKK, on a closed-end zip the measurement runs from the top of the slider to the tip of the bottom stop, and on an open-end zip from the top of the slider to the end of the open part. Coats also says it measures from the outermost point of the components and, in the closed position, from the top of the slider. The lecture note, however, measures a closed-end zip from below the bottom stop to above the top stop. Because the sources differ, write the measuring method into your quotation. If your drawings use inches, convert at 25.4 mm per inch and state the length in millimetres or centimetres on the order.

State the top and bottom tape allowances separately as well; Coats says these allowances can matter when inserting the zip. The YKK catalogue gives the following maximum tolerances according to JIS S 3015; some special products may not meet them.

How to define a zip in a quotation

Defining the zip on a single line prevents batch differences and wrong shipments. A definition should contain:

1. Tooth type and size number. Give the tooth width in millimetres and the manufacturer’s chain code as well.
2. End construction. Closed-end, open-end, two-way or double slider; for open-end, the insertion direction (the YKK catalogue lists right-hand and left-hand insertion types separately).
3. Slider. Lock type, body plating, pull style and logo if any.
4. Length, tolerance and measuring method. Including top and bottom tape allowances.
5. Tape. Fibre, colour and colour match to the fabric; expected dimensional change and colour fastness after washing.
6. Nickel status. A nickel-free or anti-nickel requirement and a test report.
7. Washing and pressing conditions. The processes the product will go through (stone washing, dyeing, dry cleaning).

An example line: “Closed-end, coil, size 3, polyester tape, auto-lock slider, 18 cm, tolerance ± 5 mm (JIS S 3015, 300 mm and under), tape colour matched to the fabric, nickel release tested to EN 1811.” Approve the tape colour and the zip action on a sample before bulk production; the steps in our sampling process guide apply here too. MOQ, price and lead time depend on the supplier and are outside this guide; request them in writing against your exact zip specification. You can find zip suppliers in the zippers category.

Quality, testing and nickel

Performance standards and tests

The European standard for general-use zips is EN 16732 (Slide fasteners (zips) - Specification). It gives performance levels and test methods for strengths such as slider attachment, bottom stop, top stop, open-end box and back-and-forth movement; it also defines levels for colour fastness to washing, dry cleaning and water, and for dimensional stability in washing and dry cleaning. It does not cover special-purpose zips such as those for diving suits. According to the EVS record, the 2025 edition is valid from May 15, 2025 and replaces the 2015 edition; this article does not quote level values, so check the current text of the standard before writing it into a contract.

The lecture note lists the tests applied to zips: resistance of the teeth to opening and twisting, attachment of the teeth to the tape, strength of the bottom and top stops, holding strength of the slider lock, tensile strength of the slider, dimensional change in washing, abrasion resistance and colour fastness. Tape size also matters: according to the lecture note, if the tape shrinks differently from the fabric during care, the seam puckers and gathers, and on a loosely woven tape the teeth can be pulled off the tape under crosswise force. For the fabric’s own shrinkage behaviour, see how to prevent fabric shrinkage. Add zip acceptance to your quality plan for each lot; our AQL quality control guide helps with the sampling logic. For testing, see the testing laboratories category.

Nickel

Zips with metal parts must also be checked for nickel compliance. In the EU, the nickel restriction is in entry 27 of Annex XVII of the REACH Regulation (EC 1907/2006). Under this entry, nickel may not be used in articles intended to come into direct and prolonged contact with the skin if the nickel release from the parts in contact with the skin exceeds 0.5 µg per square centimetre per week, and an article that does not meet this condition may not be placed on the market. The example list includes rivet buttons, tighteners, rivets, zips and metal marks used in garments. If a non-nickel coating is used, the same limit must not be exceeded for at least two years of normal use.

The reference test method is EN 1811. In notice C/2023/1604, published on December 20, 2023, the European Commission updated the reference from EN 1811:2011+A1:2015 to EN 1811:2023. The same notice lists EN 12472:2020 for the accelerated wear and corrosion simulation of coated articles. YKK says some tooth and slider surfaces contain nickel and that it offers nickel-free options; in other words, nickel must be checked on the slider surface as well as on the teeth.

In Turkey the same restriction is in entry 27 of Annex-17 of the KKDİK Regulation (Regulation on the Registration, Evaluation, Authorisation and Restriction of Chemicals). In the text published in the Official Gazette on June 23, 2017, zips on garments appear in the same example list, the limit is again 0.5 µg per square centimetre per week, and conformity is shown with test methods accepted by TSE (the Turkish Standards Institution) or the European Committee for Standardization (CEN). This information is current as of the date of this article (October 2026); regulations and their annexes can change. Before placing a product on the market, confirm the current text from the legislation source, work with an accredited laboratory and consult a chemicals-compliance specialist.

Sewing, pressing and washing: what to watch

Six points from the sewing and use warnings in the YKK catalogue that affect zip selection:

• Leave room for the slider. If the stitching is too close to the teeth, the slider catches the fabric. In lined areas, keep the stitching away from the teeth.
• Test on knitted fabric first. Before sewing in a long zip, attach it to the fabric and check the difference in stretch; YKK asks for this check especially on knitted fabric.
• Spread the load at a trouser fly. A short zip or a narrow cut puts too much load on the bottom stop; in this case YKK strongly recommends a saddle stitch.
• Protect the top stop. The sewing machine needle or foot can damage the top stop and leave a rough edge, which can cause injury. YKK suggests starting the zip 5 mm lower and comparing the result; use a plastic top stop in children’s clothing.
• Press closed, with a cloth between. The YKK catalogue gives limit temperatures of 160 °C for coil and invisible zips, 150 °C for knitted-teeth zips (FLATKNIT) and 130 °C for moulded plastic zips; the catalogue’s condition is a pressing force of 1.5 kg for 10 seconds. Do not press directly on the teeth or slider.
• Close it before washing. Keep the zip closed in washing, drying and dry cleaning; an open zip can catch on other garments and be damaged or bent.

Summary: how to choose

Start with how the product opens: open-end if the front opens completely, closed-end if one end stays closed. Then choose the tooth type for washing, pressing and appearance: metal for durable washing, coil for flexibility and lightness, moulded plastic for light, coloured outerwear and invisible for a concealed look. Set the size number by fabric weight and load, and write the tooth width in millimetres, the length, the tolerance, the slider type and the nickel requirement into the quotation. Finally, test a sample under your washing and use conditions.