Ultimate Zipper Calculator
Zipper Requirements
Pattern / Cutting Info
Tools to Also Try
How to Use the Zipper Length Calculator
Our tool takes the guesswork out of sewing math. Simply select your Project Type (Pouch, Pillow, or Garment), enter your fabric dimensions, and choose your preferred seam allowance.
The calculator provides three vital measurements:
Exact Zipper Length: The functional length (teeth only) needed for your project.
Standard Size to Buy: The closest commercial zipper size available at most craft stores.
Total Tape Length: The full length of the fabric tape needed if you are using zipper by the yard.
Understanding Zipper Measurement: Functional Length vs. Tape Length
One of the most common mistakes in sewing is measuring the wrong part of the zipper. In the sewing industry, zipper length refers to the functional span—the distance between the top stop and the bottom stop (the teeth).
Functional Length: This is the part that actually opens and closes.
Tape Length: This includes the extra "tails" of fabric at the top and bottom.
When you use our Zipper Length Calculator, we calculate the functional length you need to fit your seam-to-seam or edge-to-edge project requirements.
Zipper Length for Specific Sewing Projects
1. Zipper Size for Pouches & Bags
For a standard zipper pouch, you usually have two options:
Seam to Seam: The zipper starts and ends exactly at the side seams. This is common for flat pouches.
Edge to Edge: The zipper spans the entire width of the fabric. This is often used for boxy pouches, where the zipper length usually equals the fabric width plus a small margin for ease.
2. Zipper Length for Pillows
A standard rule for zippered pillow covers is to choose a zipper that is 2 to 4 inches (5–10 cm) shorter than the width of the pillow. This allows the zipper to be "hidden" within the seam and prevents the metal stops from poking through the corners of the pillowcase. Our calculator automatically suggests the best standard size for a snug, professional fit.
3. Zipper Length for Garments
When sewing skirts or dresses, you often need a zipper that matches the opening exactly. For a standard skirt, a 7-inch to 9-inch zipper is common. For dresses, lengths can vary from 12 to 22 inches. If your calculated length doesn't match a standard size, it is always better to buy a longer zipper and shorten it.
Choosing the Right Zipper Gauge (#3, #5, #8)
While the length is crucial the size or gauge of the zipper (the width of the teeth) also matters:
#3 Zipper: Best for lightweight projects like lace, silk and small pouches.
#5 Zipper: The universal standard for bags, hoodies and home decor.
#8 or #10 Zipper: Heavy duty zippers for luggage, tents and outdoor gear.
Frequently Asked Questions (FAQ)
What should I do if my zipper is too long?
Most nylon coil and plastic molded zippers can be easily shortened. Simply sew a new stop by zigzagging over the teeth at your desired length, then trim the excess tape. Caution: Metal zippers require pliers to remove individual teeth and move the metal stops.
Can I use a zipper that is shorter than my project?
Extending a zipper is not recommended as it leaves a gap in the opening. If your zipper is too short, the best solution is to use zipper tabs. Check the "Add Zipper Tabs" box in our calculator to see how much fabric you need for these extensions!
Is a #5 zipper 5mm wide?
Yes! The number (#3, #5, #8) represents the approximate width of the zipper teeth in millimeters when the zipper is closed.
