How to Choose Snap Fasteners: Size, Metal & Type Buying Guide

You have the press and the dies — now you need the actual snaps. But the moment you start shopping for snap fasteners, the questions pile up: what size? which metal? how many? This guide is about the consumable snaps themselves (not the tools), so you can buy the right ones with confidence and not end up with a drawer of snaps that do not suit your project.

First, the four parts of a snap

A metal snap fastener comes as a set of four pieces: a cap, a socket, a stud and a post. The cap and socket form the female (top) side; the stud and post form the male side. When you buy "100 snaps", you are buying 100 complete four-part sets. Our packs, for example, give you 100 sets = 400 parts.

What size snap should you buy?

Snap size (the visible cap diameter) drives both look and holding strength. The common sizes and where they fit:

• 10 mm: lighter garments, shirts and smaller details where you want a discreet snap.
• 12.5 mm (line 20): the everyday all-round size for shirts, blouses, light jackets and general sewing.
• 15 mm (line 24): a bigger, stronger closure for jackets, bags, workwear and outerwear.

If in doubt for general clothing, 12.5 mm is the safe middle choice; step up to 15 mm when you want a firmer hold or a more prominent look.

Which metal: stainless steel, and why it matters

Material affects durability, corrosion resistance and skin-safety:

• Stainless steel resists rust, holds tightly, and stands up to washing and outdoor exposure — the durable, low-worry choice for garments, bags and gear that get real use. All our snap fasteners are stainless steel.
• Nickel-free / skin-safe matters most for baby clothes and anything worn against sensitive skin. For babywear, always favour skin-safe options.

A quick quality check when your snaps arrive: they should fit together snugly with a firm, consistent click, and take the same effort to unsnap every time. Loose or inconsistent snaps are a sign of low-grade hardware.

Choosing by snap type

Different snap styles suit different jobs — here is what we stock and where each shines:

• Fashion spring snaps (smooth, everyday click) — for shirts, blouses and light jackets. Available in 10 mm, 12.5 mm and 15 mm.
• Heavy-duty ring snaps (system 61, stronger hold) — the 15 mm Heavy Duty Snap Button for jackets, bags and workwear that need a firm closure.
• Prong (baby) snaps (low profile, 9.5 mm) — for babywear, bibs and light fabrics, in open, capped and pearl finishes.

How many snaps do you need?

Count the snap positions in your project, then add a margin for practice and mistakes — every maker crushes a few while dialling in the press. For a first project, buying a 100-set pack gives you plenty of room to test on scraps and still finish the job. If you are trying a new size or type, buy one pack to sample before committing to a large quantity.

Match your snaps to your dies

This is the golden rule: the snap size and type must match your setting die. A 12.5 mm spring snap needs the 12.5 mm spring die; a 9.5 mm prong snap needs the 9.5 mm prong die. Keep a note of the size and system (e.g. line 20 / 54 system) so reordering is easy. If you have not set up your tools yet, see our guides on choosing a snap press machine and the right baby snap dies.

Frequently asked questions

How many parts are in one snap?
Four: cap, socket, stud and post. A pack of 100 snaps contains 400 parts — enough for 100 complete closures.

Are stainless steel snaps rustproof?
Stainless steel strongly resists rust and handles washing and outdoor use well — the durable choice for garments and gear.

Which snap is safe for baby clothes?
Use low-profile prong (baby) snaps and favour skin-safe, nickel-free options for anything worn against a baby's skin.

Can I mix snap sizes on one machine?
Yes — just use the die that matches each snap size. One press handles them all with the right dies.

Buy the right snaps once

Match the size to your garment, the type to your fabric, and the die to your snap, and you will get clean, secure closures every time. For everyday sewing, a pack of 12.5 mm stainless steel spring snaps is the ideal place to start.