Manufacturer · Fashion & Home Accessories
The sizes of sew-on snap buttons are indicated by the button diameter in millimetres or by a number assigned by the manufacturer. They are generally divided into small (about 5–8 mm) for blouses, lingerie, and children’s clothing; medium (about 9–13 mm) for dresses, skirts, and light jackets; and large (about 14 mm and above) for coats and heavy fabrics. The larger the button, the stronger the hold.
Sizes of sew-on snap buttons: how to measure
The size of a sew-on snap button is the outer diameter of each of its two parts. It is measured with calipers across the centre, between the two furthest edges. Some manufacturers use size numbers such as 4/0, 3/0, 2/0, 0, 1, 2, 3, 4 and up, where the smaller numbers with zeros are the tiniest. Since numbering varies between brands, always specify the diameter in millimetres when ordering.
Other parameters besides diameter
- Height (profile) – how much the button protrudes above the fabric; low profile is important for thin fabrics.
- Number of holes – usually 4, sometimes more for larger models.
- Snap strength – depends on size, material, and socket design.
Approximate size chart by garment type
| Category | Approximate Diameter | Typical Use |
|---|---|---|
| Miniature | about 5–6 mm | Baby clothes, doll clothes, necklines of thin blouses |
| Small | about 7–8 mm | Blouses, shirts, lingerie, straps, cuffs |
| Medium | about 9–11 mm | Dresses, skirts, light jackets, concealed plackets |
| Medium-large | about 12–13 mm | Jackets, vests, dense dresses |
| Large | about 14–21 mm | Coats, double-breasted jackets, wool garments |
| Extra large | over 21 mm | Fabric-covered buttons for coats, capes, sheepskin jackets |
This chart is indicative. The exact choice depends on fabric, load, and brand preferences.
How to choose the right size
1. According to fabric
Thin fabrics such as chiffon, silk, batiste, and knits require small, low-profile buttons. A large button will create a visible bump and its strong snap may pull the fabric. Dense fabrics like wool, velvet, denim, and tweed tolerate and require larger buttons because small ones won’t withstand the load.
2. According to load
Consider how much force the fastening will bear. A blouse neckline is hardly stressed, while the overlap of a double-breasted coat stretches with every movement. The greater the load, the larger the button size or the more buttons placed closer together.
3. According to visibility
The sew-on snap button should remain hidden. Check if the outline is visible from the outside, especially on light and thin fabrics. If it is, choose a smaller size and increase the number of buttons.
4. According to button material
Metal buttons generally hold stronger than plastic ones of the same size. Therefore, plastic models sometimes require one size larger to achieve the same security.
Small sew-on snap buttons
Small sew-on snap buttons are used where the fastening must be invisible and light: necklines, baby clothing head openings, lingerie straps, and shirt cuffs. Precise stitching is important here – small holes require thin needles and fine, strong thread.
Large sew-on snap buttons
Large sew-on snap buttons secure coat and jacket overlaps, inner facings, and concealed plackets on dense garments. Fabric-covered versions are often used to hide metal when the garment is opened.
How many buttons and spacing
The number depends on the length of the opening and the load. For concealed plackets on dresses, buttons are usually evenly spaced to prevent the fabric from gaping. Necklines or cuffs often need only one or two buttons. A practical test is to fasten a sample and check if the fabric gaps between buttons when moving.
Sew-on snap buttons or other fasteners
If an even flatter and stronger concealed fastening is needed for belts or overlaps, consider wire hooks and eyes. For visible and very strong fastening, especially on sportswear and children’s clothing, sew-on snap buttons are more suitable.
Size for fabric-covered sew-on snap buttons
When a large sew-on snap button is fabric-covered, its final diameter and height increase by the fabric thickness. This can be noticeable on thick wool fabrics. Therefore, choose a base size that reaches the desired dimensions after covering and check that the covered button still snaps clearly. Thin padded fabric or lining matching the garment face gives the cleanest result.
Size and sample testing
The most reliable way to choose a size is practical: sew two adjacent sizes on a piece of the actual fabric with the real interfacing, then fasten and unfasten them at least twenty times. Pay attention to whether the button is visible from the outside, if unfastening is comfortable, and if the fabric around it deforms.
Common size selection mistakes
- Ordering by number only without diameter in millimetres – numbering varies between manufacturers.
- Large button on thin fabric – visible from outside and pulls the fabric.
- Small button on a coat – unfastens during movement.
- Deciding without a sample on the actual fabric.
How to specify size in your inquiry
- Diameter in millimetres (and number, if known).
- Material – metal or plastic, and finish or colour.
- Fabric type and button placement on the garment.
- Quantity and whether samples in several sizes are needed.
Sew-on snap buttons in all sizes from Polkom
Polkom is a manufacturer and wholesaler of accessories for fashion, furniture, footwear, and bags with over 30 years of experience. In the sew-on snap buttons category, you will find small, medium, and large models in metal and plastic. If you are unsure about the size, request samples in two adjacent sizes and test them on your actual fabric. Contact us via the contact page.
