How to Choose the Right Zipper for Your Bag Project

Quick Answer

For most bag projects, choose a zipper based on the bag's style and function: coil zippers are flexible and great for curved seams, while molded plastic zippers are sturdy and ideal for structured bags. Measure the opening where the zipper will sit, and opt for a length that gives you a little extra to trim. Consider the weight of the fabric and whether you need a double-slide feature for luggage-style bags.

Choosing the right zipper for your bag project can feel overwhelming with so many options available. But getting it right is crucial for both function and looks. A zipper that's too short, too stiff, or the wrong type can ruin an otherwise perfect bag. This guide breaks down the key factors so you can make a confident choice every time.

Whether you're making a simple pouch or a structured tote, the zipper you select affects durability, ease of use, and the overall finish. We'll cover zipper types, sizes, lengths, and materials, plus practical decision rules to help you match the zipper to your bag's design.

Understanding Zipper Types for Bags

Zippers come in several types, but for bag making, you'll mostly choose between coil and molded plastic (also called 'plastic' or 'nylon' zippers). Coil zippers have interlocking nylon coils that are flexible and can bend around curves, making them ideal for rounded bag openings or pockets. They also tend to be lighter and quieter when opening and closing.

Molded plastic zippers have individual teeth that are stronger and more rigid. They work well for structured bags, like top-handle totes or bags that need to hold their shape. However, they can be less flexible and may not suit curved seams as well. Some bag makers prefer metal zippers for a vintage look, but these are heavier and can be harder to sew.

• Coil zippers: flexible, good for curved seams and lightweight bags.
• Molded plastic zippers: sturdy, best for structured bags and heavy fabrics.
• Metal zippers: decorative, but heavier and less flexible.

Zipper Size Selection: What the Numbers Mean

Zipper size refers to the width of the teeth or coil, typically ranging from #3 (lightweight) to #5 (heavy-duty) and beyond. For bags, #3 zippers are often used for small pouches, interior pockets, or lightweight fabrics. They have a finer profile and are easier to conceal. #5 zippers are larger and more durable, making them suitable for main bag openings, especially in bags that will carry heavier items.

When selecting the size, consider the scale of your bag and the weight of the fabric. A #3 zipper may look too delicate on a thick canvas tote, while a #5 zipper might overwhelm a delicate silk pouch. Also, think about the hardware you'll pair with it—like zipper pulls—to ensure they fit the zipper tape width.

• #3 zippers: lightweight, for small pouches and pockets.
• #5 zippers: heavy-duty, for main openings and structured bags.

Getting the Right Zipper Length

The length of the zipper should match the opening you plan to install it in. A common mistake is buying a zipper that's too short, which forces you to adjust your pattern or leave an awkward gap. On the other hand, a zipper that's too long can be trimmed to fit, but you need to ensure the zipper teeth are the correct type for cutting (coil zippers are easier to trim than molded plastic ones).

To determine the length, measure the seam where the zipper will go, including any seam allowances. If you're making a bag with a zippered top, measure the top edge of the bag front and back. For a zippered pocket, measure the pocket opening. Always add a little extra—about 1 inch—to allow for trimming and to ensure you have enough zipper tape to work with. Some suppliers offer zippers by the yard, like Sallie Tomato's Premium Zippers, which let you cut exactly what you need.

• Measure the opening and add 1 inch for trimming.
• Consider buying zippers by the yard for custom lengths.

Coil vs Plastic: Which Zipper Material Should You Choose?

When comparing coil and plastic zippers, think about the bag's function and construction. Coil zippers are made of nylon or polyester and have a continuous spiral that interlocks. They are flexible, which makes them ideal for bags with curved openings, like a bowler bag or a rounded tote. They also tend to be more forgiving when sewing over thick seams.

Plastic zippers, often called 'molded' or 'vislon' zippers, have individual teeth made of plastic that are molded onto the tape. They are stronger and more resistant to wear, making them a good choice for bags that will see heavy use, such as backpacks or diaper bags. However, they are less flexible and can be bulkier. For most handbag projects, coil zippers are a safe bet, but if you're making a structured bag that needs to hold its shape, a plastic zipper might be better.

• Coil: flexible, quiet, good for curves and lightweight bags.
• Plastic: sturdy, durable, best for structured bags and heavy loads.

Special Features: Double-Slide Zippers and More

Some bag designs call for a double-slide zipper, which opens from the center. This is perfect for luggage-style bags, bowler bags, and backpacks where you want easy access from both ends. With zippers by the yard, you can create double-slide zippers by installing two pulls on the same tape. This is a great feature to consider if you're making a bag that needs to be opened wide.

Other features to look for include self-healing coils (which can fix themselves if they separate), water-resistant coatings for outdoor bags, and decorative pulls that match your hardware. Think about how the zipper will be used: a bag that's opened and closed frequently will benefit from a smoother, more durable zipper.

• Double-slide zippers: ideal for luggage-style bags and backpacks.
• Look for self-healing coils or water-resistant options for specific needs.

Decision Rules for Choosing Your Zipper

• If your bag has curved seams: Choose a coil zipper because it bends easily around curves without buckling. Coil zippers are your go-to for rounded bag openings.
• If your bag is structured and heavy-duty: Opt for a molded plastic zipper with a #5 size to handle the weight and maintain shape. Plastic zippers provide the sturdiness needed for structured bags.
• If you need a custom length or double-slide: Buy zippers by the yard so you can cut exactly what you need and create double-slide zippers for luggage-style bags. Zippers by the yard offer flexibility and reduce waste.

Products to Consider

• Tula Pink Black Nylon Coil Zippers: Premium Zippers by the Yard, designed for bag making, accessories, home décor, apparel, and more. Cut the exact length you need to reduce waste, save money, customize your projects, and achieve a polished, professional finish every time! Plus, create double-slide zippers that open from the center, which are perfect for luggage-style bags, bowler bags, and backpacks. If you prefer coil zippers for their flexibility and want to customize lengths without waste, these zippers by the yard are a practical choice. You can also make double-slide zippers for specific bag styles.
• Jenny Hardware Kit: Give your Jenny bag a clean, polished, and professional finish with this all-in-one Jenny Hardware Kit. Thoughtfully curated by Sallie Tomato, this kit includes all the essential metal components needed to complete your project with confidence—no extra shopping required. Each piece is crafted with a smooth, high-quality finish that adds durability, shine, and style to your handmade bag. When choosing a zipper, consider the hardware you'll pair with it, such as zipper pulls and D-rings. This kit ensures your hardware matches and is high-quality, so you can focus on the zipper selection.

Fit Guidance

Best For

• Sewists making handbags, totes, or pouches who want a flexible, easy-to-sew zipper.
• Bag makers who need custom lengths or double-slide zippers for specific bag designs.

Not For

• Projects requiring ultra-heavy-duty zippers for industrial use or extremely thick materials.
• Bags that demand a specific metal or decorative zipper aesthetic.

Choosing the right zipper for your bag project comes down to understanding the type, size, length, and material that best fits your design. By following these decision rules and considering the trade-offs, you'll select a zipper that functions smoothly and looks professional. Remember to measure carefully, and don't hesitate to buy zippers by the yard for maximum flexibility.