A Comprehensive Guide to Heat Shrink Tubing: Choosing The Correct Size For Your Requirements

C Tie® Heat Shrink Tubing is available in a wide variety of options.

It is important to consider the following factors when selecting the correct size for your application.

  1. Bundle Diameter: The primary consideration when selecting heat shrink tubing is the diameter of the bundle you intend to cover. Measure the widest part of the item and choose a size that can comfortably accommodate that diameter. It's better to opt for a slightly larger size to allow for easier installation.


  1. Shrink Ratio: C Tie® Heat shrink tubing is available in various shrink ratios,  ranging from 2:1 to 4:1 ratio. The shrink ratio indicates how much the tubing will reduce in size when heated. For example, a 2:1 shrink ratio means that a 2.4mm tubing will shrink to a recovered diameter of 1.2mm. A higher shrink ratio is advised for applications where the tubing needs to fit snugly over irregular sized bundles.


Lay Flat Width vs. Inside Diameter Measurements

Another important factor to consider when selecting the size of heat shrink tubing is the lay flat width. The lay flat width is the width of the heat shrink tubing when flattened. This is not to be confused with the inside diameter of the tubing, which is how the sizes are listed.

It is quite common for the user to measure the lay flat width of the heat shrink tubing and request this measurement as the size when in fact they require a smaller size based on the inside diameter.

A list of all of the outside diameters and their respective lay flat widths can be found on our website.


Calculating the correct heat shrink tubing size based on the lay-flat width or inside diameter

A simple calculation can be used to calculate the correct size of heat shrink tubing required based on the flat width measurement provided.

This is shown below:

Lay Flat Width x 0.6366 = Inside Diameter

Conversely, to find the lay flat width of the heat shrink tubing, the following formula can be used:

Inside Diameter ÷ 0.6366 = Lay Flat Width             


Further information on the full range can be found on our website - Heatshrink & Cable Sleeving - C Tie

Looking for prices? Please contact us by email on sales@ctie.co.uk or call us on +44 1737 760645.


C Tie (UK) Ltd
Unit 5, Axiom Business Park, 41 Balcombe Road
Horley, Surrey RH6 7HF
T. +44 (0)1737 760645
E. sales@ctie.co.uk