Heat Shrink Tubing Size Guide

Selecting the right heat shrink tubing size is vital for ensuring optimal protection and insulation in your projects. This guide will help you understand heat shrink tubing ratios and provide size charts for our products, making it easier to choose the perfect fit for your wires and cables.

How is heat shrink tubing made?

The manufacture of polyolefin heat-shrink tubing typically involves 5 key stages:

1. Extrusion - Polyolefin resin is melt-extruded through a circular die to form a seamless tube.


2. Cross-linking - While still hot, the extruded tube passes through an electron-beam irradiation unit (or is mixed with a chemical cross-linking agent and then heated). This creates a three-dimensional network within the polymer, improving thermal stability and “memory” (the ability to recover its original dimensions when reheated).


3. Expansion - The cross-linked tube is reheated above its crystalline melting point and mechanically expanded (either by internal air pressure or by stretch dies) to a diameter typically two to three times its original size (creating 2:1 or 3:1 ratio heat shrink).


4. Cooling - Immediately after expansion, it is rapidly cooled (often by passing through a water bath), locking in the enlarged dimensions.


5. Finishing and Testing - The expanded tubing is cut to standard coil lengths. Samples undergo quality checks for shrink ratio, tensile strength, elongation, wall thickness and temperature-recovery performance. Accepted batches are then wound onto reels, labelled and packed for distribution.

Selecting the right heat shrink size

Understanding heat shrink tubing ratios is key to selecting the right size for your project. The shrink ratio indicates how much the tubing will contract when heated. Common ratios include 2:1 (shrinks to half its original diameter), 3:1 (shrinks to one-third), and 4:1 (shrinks to one-quarter). These shrink ratios offer increasing levels of flexibility for covering varied shapes and sizes. 

To choose the correct size, measure the widest part of the item you're covering, like a connector. The heat shrink size should be at least 10%-20% larger than the widest part of your connection. This ensures a snug fit once shrunk, providing optimal insulation and protection.

Dual-wall adhesive-lined heat shrink can form an environmental seal for connections that require moisture-proofing.

Heat Shrink Size Charts

• EHS-G2 2:1 General Purpose Heat Shrink
  
• RNF-100 2:1 General Purpose Heat Shrink
  
• EHS-G3 3:1 General Purpose Heat Shrink
  
• ZHTM 2:1 Low Toxicity Heat Shrink
  
• 3:1 Adhesive-Lined Heat Shrink
  
• 4:1 Adhesive-Lined Heat Shrink
  

EHS-G2 2:1 General Purpose Heat Shrink

The expressPRO 2:1 general purpose polyolefin heat shrink is our most popular tubing. It comes in a variety of colours and lengths, including mini reels for smaller projects and industrial-size reels of up to 300 metres in the most popular colours.

• Colours: Black, White, Clear, Yellow, Green/Yellow, Brown, Red, Green, Dark Blue, Light Blue, Grey, Orange, and Violet
• Material: Polyolefin
• Operating Temperature: -40 to +135°C
• Recovery Temperature: +80°C
• Flame Retardant
• Halogen-Free
• Resistant to: Petrol, H-515 Hydraulic Fluid, O-148 Lubricating Oil
• Standards: UL224 VW1, RoHS 2, AMS-DTL-23053/5 Cl 1&2 and CSA 066150

Available Colours	Unshrunk (Supplied) Diameter	Shrunk (Recovered) Diameter
Large Spools Mini Reels	1.2mm (3/64”)	0.6mm (1/32”)
Large Spools Mini Reels	1.6mm (1/16”)	0.8mm (³/₃₂”)
Large Spools Mini Reels	2.4mm (3/32”)	1.2mm (3/64”)
Large Spools Mini Reels	3.2mm (1/8”)	1.6mm (1/16”)
Large Spools Mini Reels	4.8mm (3/16”)	2.4mm (3/32”)
Large Spools Mini Reels	6.4mm (¼”)	3.2mm (⅛”)
Large Spools Mini Reels	9.5mm (⅜”)	4.8mm (3/16”)
Large Spools Mini Reels	12.7mm (½”)	6.4mm (¼”)
Large Spools Mini Reels	19.1mm (¾”)	9.5mm (⅜”)
Large Spools Mini Reels	25.4mm (1”)	12.7mm (½”)
Large Spools	38.1mm (1 1/2”)	19.1mm (¾”)
Large Spools	50.8mm (2”)	25.4mm (1”)
Large Spools	76.2mm (3”)	38.1mm (1 1/2”)
Large Spools	101.6mm (4”)	50.8mm (2”)

RNF-100 2:1 General Purpose Heat Shrink

RNF-100 is a 2:1 heat shrink tubing manufactured by TE Connectivity, formerly Raychem. It’s available in larger size reels for industrial use, up to 600m for the most popular sizes.

• Colours: Black, White, Clear
• Material: Polyolefin
• Operating Temperature: -55°C to +135°C
• Recovery Temperature: +95°C
• Flame Retardant
• Standards: UL E35586 600V 125ºC, CSA LR31929 600V 125ºC, Military AMS-DTL-23053/5 Class 1 Def. Stan. 59-97 Type 2B, Industry VDE 0341 Pt 9005 Type A and B

Colours	Unshrunk (Supplied) Diameter	Shrunk (Recovered) Diameter
	1.2mm (3/64”)	0.6mm (1/32”)
	1.6mm (1/16”)	0.8mm (³/₃₂”)
	2.4mm (3/32”)	1.2mm (3/64”)
	3.2mm (⅛”)	1.6mm (1/16”)
	4.8mm (3/16”)	2.4mm (3/32”)
	6.4mm (¼”)	3.2mm (⅛”)
	9.5mm (⅜”)	4.8mm (3/16”)
	12.7mm (½”)	6.4mm (¼”)
	19.1mm (¾”)	9.5mm (⅜”)
	25.4mm (1”)	12.7mm (½”)
	31.8mm (1 ¼”)	15.9mm (⅝”)
	38.1mm (1 1/2”)	19.1mm (¾”)
	50.8mm (2”)	25.4mm (1”)
	76.2mm (3”)	38.1mm (1 1/2”)
	101.6mm (4”)	50.8mm (2”)
	127mm (5”)	63.5mm (2 ½”)

EHS-G3 3:1 General Purpose Heat Shrink

The expressPRO 3:1 general purpose polyolefin heat shrink has a larger shrink ratio than 2:1 heat shrink tubing. This allows it to be used over larger connectors and smaller wires and still shrink to a tight fit.

• Colours: Black, White, Clear, Yellow, Red, Green, Light Blue
• Material: Polyolefin
• Operating Temperature: -55 to +135°C
• Recovery Temperature: +100°C
• Flame Retardant
• Standards: AMS-DTL 23053/5, DEF STAN 59-97, VG 95343 Pt5, UL/CSA : UL 224 VW1, 600V, 125°C. CSA 600V, 125°C

Colours	Unshrunk (Supplied) Diameter	Shrunk (Recovered) Diameter
	3mm	1mm
	6mm	2mm
	9mm	3mm
	12mm	4mm
	18mm	6mm
	24mm	8mm
	39mm	13mm

ZHTM 2:1 Low Toxicity Heat Shrink

ZHTM is a flexible, black, thick-wall, 2:1 heat shrink tubing from TE Connectivity with excellent fire safety characteristics. It’s commonly used in marine applications, mass transit systems, and offshore installations

• Colour: Black
• Material: Polyolefin
• Operating Temperature: -30 to +105°C
• Recovery Temperature: +80°C
• Low smoke emission and low evolution of acid gases
• Retains good mechanical and fluid resistance properties
• Insulate and protect cables, harnesses, electrical and electronic components

3: 1 Adhesive Lined Heat Shrink

Adhesive Lined Heat Shrink is used to seal connectors, wire splices, break-outs, cable jackets and electrical components. This dual wall semi-flexible polyolefin 3:1 heat shrink is glue-lined to create a moisture-proof seal after shrinking.

EHS-A3 is our own expressPRO brand.

ATUM is TE Connectivity brand heat shrink.

• Colour: Black
• Material: Polyolefin
• Operating Temperature: -55 to +110°C
• Recovery Temperature: +80°C
• Halogen-free

4: 1 Adhesive Lined Heat Shrink

ATUM 4:1 semi-flexible polyolefin is an adhesive-lined heat shrink tubing manufactured by TE Connectivity. The adhesive melts to form an environmental barrier to prevent moisture penetration. Used to seal connectors, wire splices, break-outs, cable jackets and electrical components

• Colour: Black
• Material: Polyolefin
• Operating Temperature: -55 to +110°C
• Recovery Temperature: +80°C
• Widely used across military, aerospace, marine and automotive industries
• Excellent mechanical protection, and bonds to plastics, rubbers and metals

Got questions about heat shrink?

Our friendly and knowledgeable sales team is happy to help. If you've got questions not covered in our guide, or if you're looking for something that's not listed on our website, Express Electrical is here for you.

Give us a call at +44 (0)141 941 3689 or email sales@expresselectrical.co.uk. We're open from 8:00-17:00 Monday-Friday.