Blind String Information and Measuring

String that is used in blinds and shades is 100% polyester and is woven to withstand the rigors of blind operation.  This type of string is NOT commonly sold in stores of any kind, so it must be either special ordered from a blind manufacturer, or ordered from Fix My Blinds.

There are many different diameter sizes of blind string and it is commonly measured in millimeters.  String for cloth shades such as Cellular, Honeycomb and Pleated Shades, are usually .9MM or 1.2MM.  String for Mini-Blinds is usually 1.4MM or 1.6MM.  String for Wood, Faux Wood or Venetian Blinds can range from 1.6MM to 2.2MM.  String for Roman, Woven Wood and Vertical Blinds can range from 1.8MM to 4.0MM.  See table below:

String size blog


To determine the diameter of string you need, follow the simple string wrap and measure technique in the video below:



What this technique does is effectively allow you to measure ten widths, or diameters, of the string, then convert it to inches and compare to the measurements on the Fix My Blinds website to determine the diameter of one width, or diameter.  We provide the measurements for determining string diameter for blind string between .9MM and 4.0MM.

blind string size gauge range


  1. My blinds currently have 1.6mm string, but it seems really thin, and has already broken once. Would it be a problem if I ordered 1.8mm or 2mm string instead?

    1. You should be okay to go up to 1.8mm or even 2.0mm. I would look in the headrail and make sure nothing is rubbing against the string. Also the other blinds may be a different manufacturer, causing them to have a different size string. Let me know if you have any further questions.

  2. I was searching for the proper way to fix the one string on my wooden blind but I did not find that in troubleshooting.It’s the string that opens & closes the wooden slats. It is located to the left side of the blind; when I open the blind, the slats are still tilted and I’m not getting proper lighting in my bedroom….can you please help me with this problem?

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