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Calcimator

Zipper Length Calculator

Calculate the correct zipper length for your garment opening. Accounts for zipper type (regular, invisible, separating) and seam allowances.

Inputs

in
in

Results

Buy This Length

7 in

≈ 2 credit cards

Minimum Zipper Length7 in
Total Seam Opening8.25 in
Tape Length (incl. ends)8 in
Extra for Zipper Type0 in
How to Use This Calculator
  1. Enter the zipper opening length (inches) -- measure the gap in the seam.
  2. Set seam allowance (inches) and select zipper type (regular, lapped, invisible, or centered).
  3. Review recommended zipper length, minimum zipper length, seam opening, and tape extension.
  4. Standard zippers come in 2-inch increments -- round up to the next standard length.
  5. For invisible zippers, purchase a zipper 1-2 inches longer than the opening to allow for the pull stop.

How the result changes with Opening Length

Opening LengthBuy This Length
6.77 in
1616 in
2730 in
3636 in

What each input means

Opening Length
Length of the garment opening where the zipper will be inserted
Seam Allowance
Seam allowance width on each side of the zipper
Zipper Type
1=Regular, 2=Invisible (+0.25"), 3=Separating (+0.5")

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Opening Length = 7, Seam Allowance = 0.625, Zipper Type = 1 = 3 input(s) provided
  2. Calculate Buy This Length
    Buy This Length
    7 = 7
  3. Calculate Minimum Zipper Length
    Minimum Zipper Length
    7 = 7
  4. Calculate Total Seam Opening
    Total Seam Opening
    8.25 = 8.25

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