Zipper Length Calculator

Work out zipper length instantly with clear inputs, formula shown and shareable results.

About Zipper Length Calculator

Zip length is the opening plus ease plus an allowance that depends on type, since invisible zips need extra above the opening for the pull to clear. Zips are only sold in standard lengths, so rounding up and shortening from the top is normal practice rather than a compromise.

Formula

Zip length

length = opening + ease + type allowance

Worked example

With the default values below, Zipper Length Calculator returns Zip length required of 25.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Opening lengthminimum 1 cm: 22 cm
Ease to addminimum 0 cm: 2 cm
Zip typeone of Closed end, Open end (separating), Invisible: Closed end

Results

Zip length required: 25.00 cm
Nearest standard zip size: 25 cm
Total tape length including ends: 31.0 cm
Extra length over the requirement: 0.00 cm

Step by step

1Values used
2Zip length
3Zip length required= 25.00 cm
4Nearest standard zip size= 25 cm
5Total tape length including ends= 31.0 cm
6Extra length over the requirement= 0.00 cm

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Zipper Length figure worked out?

length = opening + ease + type allowance. Zip length is the opening plus ease plus an allowance that depends on type, since invisible zips need extra above the opening for the pull to clear.

Why does this matter?

Zips are only sold in standard lengths, so rounding up and shortening from the top is normal practice rather than a compromise.

What do I need to enter?

Enter opening length, ease to add, zip type. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.