How to Calculate Zipper Length
A Comprehensive Guide
When working with garments, bags, or upholstery, selecting
and calculating the correct zipper length is crucial for ensuring functionality
and aesthetics. Here's a step-by-step guide on how to calculate zipper length
accurately.
What is Zipper Length?
The zipper length refers to the total length of the zipper
chain or teeth, measured from the top stopper to the bottom stopper, excluding
the tape extension. The zipper tape’s extra length is generally not included in
this calculation but is essential for sewing purposes.
Factors to Consider Before Calculating Zipper Length
- Purpose
of the Zipper:
- For
garments, the zipper length depends on the size and type of opening
(e.g., a fly, a jacket, or a skirt).
- For
bags, the length corresponds to the opening’s dimensions.
- Type
of Zipper:
- Closed-End
Zipper: Commonly used in bags and boots.
- Open-End
Zipper: Typically found in jackets and coats.
- Invisible
Zipper: Often used in dresses or skirts for a seamless look.
- Garment
or Product Design: The design determines the exact placement and
length required for the zipper.
Steps to Calculate Zipper Length
- Measure
the Opening Length:
- Use
a measuring tape to determine the exact length of the opening where the
zipper will be installed.
- Determine
the Functional Length:
- This
is the length from where the zipper needs to open and close completely.
For example, in a jacket, it starts at the hem and goes up to the collar.
- Account
for Seam Allowance:
- Add
1–2 cm (or as per the sewing design) for seam allowance. This is
particularly important for zippers sewn into seams like skirts and
dresses.
- Consider
Tape Extensions:
- While
the chain length remains fixed, manufacturers often add 2–4 cm extra to
the tape for sewing purposes. This extra length ensures ease of
installation.
- Choose
the Nearest Standard Size:
- Zippers
are available in standard sizes, such as 6", 8", 10", etc.
Select the nearest size or customize the length if needed.
Example Calculation
Scenario: A zipper is required for a skirt with an 18
cm back opening.
- Measure
the Opening: 18 cm.
- Add
Seam Allowance: 18 cm + 1 cm = 19 cm.
- Select
a Zipper Size: Choose a standard 20 cm zipper for this requirement,
ensuring the extra tape accommodates sewing needs.
Zipper Length in Specialty Applications
- Bags
and Pouches: For curved openings, measure the curve with flexible tape
to get the accurate length.
- Cushion
Covers: Add a few extra centimeters to allow the cushion to fit
snugly.
Tips for Accuracy
- Always
measure twice to avoid errors.
- If the
zipper will be shortened, ensure it has metal or plastic teeth that can be
easily cut.
- Consult
with your supplier for custom lengths or non-standard zipper sizes.
Conclusion
Calculating zipper length is a straightforward yet vital
step in sewing and manufacturing. By considering the purpose, measuring
accurately, and accounting for seam allowances and tape extensions, you can
ensure that your zipper not only fits perfectly but also enhances the overall
functionality and aesthetics of your product.
For more textile tips and techniques, visit Learn Easy
Textile.
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