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Choosing the right size of heat shrink tubing should be simple. Unfortunately, once you start comparing cable diameters, conductor sizes, AWG sizes, shrink ratios and adhesive-lined options, it can become more annoying than it has any right to be.
So, we've put together our ultimate heat shrink size guide to make choosing the right tubing as straightforward as possible.
There are two main things to decide: First, whether you need general-purpose or adhesive-lined heat shrink tubing. Second, what diameter and shrink ratio you need.
If you're repairing, joining or terminating cables, 3:1 adhesive-lined heat shrink is usually the best place to start. The larger shrink ratio makes sizing more forgiving, while the heat-activated adhesive helps create a more secure seal against moisture, water and dust.
General-purpose heat shrink is a better choice when you simply need electrical insulation, cable protection, bundling, identification or a neat finish and don't require the tubing to bond to the cable underneath.
If you already know the outside diameter (OD) of the cable, wire, bundle or component you need to cover, use our diameter selector tables below. This is the most accurate way to choose your heat shrink.
If you only know the conductor size in mm² or AWG, scroll down to our approximate cable size guide. We've included realistic finished cable diameters, including insulation, to help you choose a suitable heat shrink size.
Important: Always measure the widest part that the heat shrink needs to pass over. If it needs to slide over a connector, crimp, terminal or splice before shrinking onto a smaller cable, the diameter of that larger component also needs to be considered.
General Purpose or Adhesive-Lined Heat Shrink?
Before choosing a diameter, it's worth deciding which type of heat shrink is best for the job.
General-purpose heat shrink is single-wall tubing. It's ideal when you mainly need electrical insulation, cable protection, bundling, identification or a neat finish.
Adhesive-lined heat shrink, also known as dual-wall heat shrink, contains an inner layer of heat-activated adhesive. As the tubing shrinks, the adhesive melts and flows around the cable, connector or splice to create a much more complete environmental seal.
| Application | Recommended Type | Why? |
|---|---|---|
| Basic electrical insulation | General Purpose | Simple, flexible insulation without needing an environmental seal. |
| Cable identification or colour coding | General Purpose | Ideal where the main purpose is identification, organisation or appearance. |
| Bundling wires and cables | General Purpose | Provides a neat protective outer layer without adhesive bonding the bundle together. |
| Extra mechanical or abrasion protection in a dry environment | General Purpose | Suitable where protection is required but moisture sealing is not. |
| Needs to pass over a larger connector before shrinking onto a cable | 3:1 General Purpose | The higher shrink ratio gives considerably more flexibility than 2:1 tubing. |
| Outdoor or exposed electrical connections | 3:1 Adhesive-Lined | The adhesive lining helps seal the connection against moisture, water and dust. |
| Wire splices and cable joints | 3:1 Adhesive-Lined | Provides insulation together with an environmental seal around the splice. |
| Crimp terminals and cable terminations | 3:1 Adhesive-Lined | The adhesive can seal around the transition between the cable and termination. |
| Automotive wiring and exposed wiring harnesses | 3:1 Adhesive-Lined | Useful where wiring may be exposed to moisture, dirt and demanding conditions. |
| Machinery and industrial wiring requiring environmental protection | 3:1 Adhesive-Lined | Provides insulation, mechanical protection and additional sealing. |
| Repairing damaged cable insulation where moisture protection is important | 3:1 Adhesive-Lined | The dual-wall construction provides both a protective outer layer and an adhesive seal. |
| Applications that may need to be easily removed or reworked later | General Purpose | Single-wall tubing does not intentionally bond itself to the cable or component underneath. |
In simple terms: If you just need insulation, identification or protection, general-purpose heat shrink is normally the right choice. If you need to protect a connection from moisture, water or dust, or want a more permanent sealed finish around a splice or termination, choose adhesive-lined heat shrink.
3:1 Adhesive-Lined Heat Shrink Size Guide
For many cable joints, electrical repairs, terminations, automotive applications and installations exposed to moisture or dirt, we'd recommend starting with 3:1 adhesive-lined heat shrink tubing.
Adhesive-lined heat shrink has a heat-shrinkable outer wall and an inner layer of heat-activated adhesive. As the tubing shrinks, the adhesive melts and flows around the cable, connector or joint to provide additional sealing and mechanical protection.
The 3:1 shrink ratio also makes it particularly useful where the tubing needs to pass over a larger connector, crimp or splice before shrinking tightly onto a smaller cable.
If you know the outside diameter of the cable or object, use the table below. Our recommended sizing ranges leave approximately 20% clearance from both extremes of the tubing's shrink capability, helping the tubing slide over the object easily while still ensuring plenty of recovery when heated.
| Recommended Cable / Object OD | Heat Shrink Size | Fully Recovered ID | 1.2m Piece | Mini Reel | Bulk Reel |
|---|---|---|---|---|---|
| 1.2-2.6mm | 3.2mm | 1.0mm | 3.2mm 1.2m Piece | 3.2mm Mini Reel | 3.2mm Bulk Reel |
| 1.9-3.8mm | 4.8mm | 1.6mm | 4.8mm 1.2m Piece | 4.8mm Mini Reel | 4.8mm Bulk Reel |
| 2.4-5.1mm | 6.4mm | 2.0mm | 6.4mm 1.2m Piece | 6.4mm Mini Reel | 6.4mm Bulk Reel |
| 3.6-7.6mm | 9.5mm | 3.0mm | 9.5mm 1.2m Piece | 9.5mm Mini Reel | 9.5mm Bulk Reel |
| 4.8-10.2mm | 12.7mm | 4.0mm | 12.7mm 1.2m Piece | 12.7mm Mini Reel | 12.7mm Bulk Reel |
| 7.2-15.3mm | 19.1mm | 6.0mm | 19.1mm 1.2m Piece | 19.1mm Mini Reel | 19.1mm Bulk Reel |
| 10.2-20.3mm | 25.4mm | 8.5mm | 25.4mm 1.2m Piece | 25.4mm Mini Reel | 25.4mm Bulk Reel |
| 15.2-30.5mm | 38.1mm | 12.7mm | - | - | 38.1mm Bulk Reel |
When should you choose adhesive-lined heat shrink? It's particularly useful for cable joints, crimp terminals, electrical repairs, automotive wiring, machinery, outdoor installations and other situations where additional protection from moisture, water, dirt or dust is useful.
Tip: When using adhesive-lined tubing over a connector, splice or terminal, check both dimensions. The tubing needs to be large enough before shrinking to pass over the widest part, while still being able to recover tightly enough around the smaller cable or component that needs sealing.
3:1 General Purpose Heat Shrink Size Guide
Choose 3:1 general-purpose heat shrink when you want the flexibility of a high shrink ratio but don't need an adhesive seal.
It's ideal where the tubing needs to pass over a connector, splice or other larger component before recovering onto a smaller cable, as well as for general insulation, cable protection, bundling and identification.
Because there is no adhesive layer, general-purpose tubing is also easier to remove or replace later if the installation needs to be reworked.
| Recommended Cable / Object OD | Heat Shrink Size | Fully Recovered ID | Mini Reel | Bulk Reel |
|---|---|---|---|---|
| 0.6-1.2mm | 1.5mm | 0.5mm | - | 1.5mm Bulk Reel |
| 1.2-2.4mm | 3mm | 1mm | 3mm Mini Reel | 3mm Bulk Reel |
| 1.8-3.6mm | 4.5mm | 1.5mm | 4.5mm Mini Reel | 4.5mm Bulk Reel |
| 2.4-4.8mm | 6mm | 2mm | 6mm Mini Reel | 6mm Bulk Reel |
| 3.6-7.2mm | 9mm | 3mm | 9mm Mini Reel | 9mm Bulk Reel |
| 4.8-9.6mm | 12mm | 4mm | 12mm Mini Reel | 12mm Bulk Reel |
| 6.0-12.0mm | 15mm | 5mm | - | 15mm Bulk Reel |
| 7.2-14.4mm | 18mm | 6mm | 18mm Mini Reel | 18mm Bulk Reel |
| 9.6-19.2mm | 24mm | 8mm | 24mm Mini Reel | 24mm Bulk Reel |
| 12.0-24.0mm | 30mm | 10mm | - | 30mm Bulk Reel |
| 15.6-31.2mm | 39mm | 13mm | - | 39mm Bulk Reel |
2:1 General Purpose Heat Shrink Size Guide
2:1 general-purpose heat shrink is ideal for straightforward insulation, cable protection, bundling, colour coding and identification where the diameter of the object doesn't change dramatically along the length being covered.
It's generally the simplest and most economical option when you don't require an adhesive seal or the wider recovery range of 3:1 tubing.
Our recommended ranges leave some room for the tubing to slide easily over the cable before heating while still ensuring that it shrinks sufficiently for a good fit. As a general rule, we recommend using 2:1 tubing where the object diameter is approximately 60%-80% of the tubing's original internal diameter.
| Recommended Cable / Object OD | Heat Shrink Size | Fully Recovered ID | Mini Reel | Bulk Reel |
|---|---|---|---|---|
| 0.7-1.0mm | 1.2mm | 0.6mm | 1.2mm Mini Reel | 1.2mm Bulk Reel |
| 1.0-1.3mm | 1.6mm | 0.8mm | 1.6mm Mini Reel | 1.6mm Bulk Reel |
| 1.4-1.9mm | 2.4mm | 1.2mm | 2.4mm Mini Reel | 2.4mm Bulk Reel |
| 1.9-2.6mm | 3.2mm | 1.6mm | 3.2mm Mini Reel | 3.2mm Bulk Reel |
| 2.9-3.8mm | 4.8mm | 2.4mm | 4.8mm Mini Reel | 4.8mm Bulk Reel |
| 3.8-5.1mm | 6.4mm | 3.2mm | 6.4mm Mini Reel | 6.4mm Bulk Reel |
| 5.7-7.6mm | 9.5mm | 4.75mm | 9.5mm Mini Reel | 9.5mm Bulk Reel |
| 7.6-10.2mm | 12.7mm | 6.35mm | 12.7mm Mini Reel | 12.7mm Bulk Reel |
| 9.6-12.8mm | 16mm | 8mm | - | 16mm Bulk Reel |
| 11.5-15.3mm | 19.1mm | 9.55mm | 19.1mm Mini Reel | 19.1mm Bulk Reel |
| 15.2-20.3mm | 25.4mm | 12.7mm | 25.4mm Mini Reel | 25.4mm Bulk Reel |
| 18.0-24.0mm | 30mm | 15mm | - | 30mm Bulk Reel |
| 22.9-30.5mm | 38.1mm | 19.05mm | - | 38.1mm Bulk Reel |
| 30.5-40.6mm | 50.8mm | 25.4mm | - | 50.8mm Bulk Reel |
| 45.7-61.0mm | 76.2mm | 38.1mm | - | 76.2mm Bulk Reel |
| 61.0-81.3mm | 101.6mm | 50.8mm | - | 101.6mm Bulk Reel |
| 72-96mm | 120mm | 60mm | - | 120mm Bulk Reel |
| 90-120mm | 150mm | 75mm | - | 150mm Bulk Reel |
| 108-144mm | 180mm | 90mm | - | 180mm Bulk Reel |
| 126-168mm | 210mm | 105mm | - | 210mm Bulk Reel |
| 138-184mm | 230mm | 115mm | - | 230mm Bulk Reel |
| 150-200mm | 250mm | 125mm | - | 250mm Bulk Reel |
Heat Shrink Size Guide by Cable Size and AWG
What if you don't know the finished outside diameter of your cable, but you do know that it's 2.5mm², 16mm², 95mm² or a particular AWG size?
Conductor size and cable diameter are not the same thing. A conductor size such as 6mm² describes the cross-sectional area of the conductor itself, while the finished cable also includes insulation. The thickness of that insulation varies depending on the type of cable, voltage rating, manufacturer and construction.
The table below therefore provides a practical approximation based on typical single-core flexible PVC-insulated cable. We've included the approximate finished outside diameter used for each recommendation so you can see what the suggested heat shrink size is based on.
| Conductor Size | Approx. AWG Equivalent | Typical Insulation Thickness | Approx. Finished Cable OD | Suggested 3:1 Adhesive-Lined | Suggested 3:1 General Purpose | Suggested 2:1 General Purpose |
|---|---|---|---|---|---|---|
| 0.5mm² | Approx. 21 AWG | Approx. 0.8mm | Approx. 2.7mm | 4.8mm | 4.5mm | 4.8mm* |
| 0.75mm² | Approx. 19 AWG | Approx. 0.8mm | Approx. 2.9mm | 4.8mm | 4.5mm | 4.8mm* |
| 1mm² | Approx. 18 AWG | Approx. 0.8mm | Approx. 3.0mm | 4.8mm | 4.5mm | 4.8mm |
| 1.5mm² | Approx. 16 AWG | Approx. 0.8mm | Approx. 3.3mm | 4.8mm | 4.5mm | 4.8mm |
| 2.5mm² | Approx. 14 AWG | Approx. 0.8mm | Approx. 3.8mm | 4.8mm | 6mm | 4.8mm |
| 3-3.3mm² | Approx. 12 AWG | Approx. 0.8mm | Approx. 4.0mm | 6.4mm | 6mm | 6.4mm |
| 4mm² | Approx. 12 AWG | Approx. 0.8mm | Approx. 4.4mm | 6.4mm | 6mm | 6.4mm |
| 6mm² | Approx. 10 AWG | Approx. 0.8mm | Approx. 4.9mm | 6.4mm | 9mm | 6.4mm |
| 10mm² | Approx. 8 AWG | Approx. 1.0mm | Approx. 6.3mm | 9.5mm | 9mm | 9.5mm |
| 16mm² | Approx. 6 AWG | Approx. 1.0mm | Approx. 8.1mm | 12.7mm | 12mm | 12.7mm |
| 25mm² | Approx. 4 AWG | Approx. 1.2mm | Approx. 9.4mm | 12.7mm | 12mm | 12.7mm |
| 35mm² | Approx. 2 AWG | Approx. 1.2mm | Approx. 10.9mm | 19.1mm | 15mm | 16mm |
| 50mm² | Approx. 1 AWG | Approx. 1.4mm | Approx. 13.1mm | 19.1mm | 18mm | 19.1mm |
| 70mm² | Approx. 2/0 AWG | Approx. 1.4mm | Approx. 15.1mm | 19.1mm | 24mm | 19.1mm |
| 95mm² | Approx. 3/0 AWG | Approx. 1.6mm | Approx. 16.1mm | 25.4mm | 24mm | 25.4mm |
| 120mm² | Approx. 4/0 AWG | Approx. 1.6mm | Approx. 17.9mm | 25.4mm | 24mm | 25.4mm |
| 150mm² | Approx. 250 MCM | Approx. 1.8mm | Approx. 20.2mm | 25.4mm | 30mm | 25.4mm |
| 185mm² | Approx. 350 MCM | Approx. 2.0mm | Approx. 22.9mm | 38.1mm | 30mm | 30mm |
| 240mm² | Approx. 450 MCM | Approx. 2.2mm | Approx. 24.4mm | 38.1mm | 39mm | 38.1mm |
*Very small cables around 2.7-2.9mm OD sit close to the gap between our preferred 3.2mm and 4.8mm 2:1 sizing ranges. We suggest 4.8mm as the more practical general option, but measuring the actual cable is recommended.
Please remember: The conductor-size table is intended as a general guide only. Finished cable diameters can vary considerably between thin-wall automotive cable, tri-rated cable, battery cable, welding cable, rubber-insulated cable and other constructions. Where possible, measure the actual outside diameter and use the diameter tables above.
If you are covering a splice, connector, terminal or other component that is wider than the cable itself, choose the heat shrink based on the largest diameter it must pass over as well as the final diameter it must recover onto.
What About Assortment Kits?
Heat shrink tubing assortment kits are a handy backup option for those occasional sizes you don't use often. If you regularly use heat shrink, however, we'd recommend buying your most commonly used sizes on a reel instead. Assortment kits only contain a small number of pieces in each diameter, so while they're great for keeping a useful selection to hand, they're generally not the most economical option for frequently used sizes.
Shop Heat Shrink Tubing by Colour
The direct product links in the selector tables above primarily refer to our black heat shrink ranges. If you need another colour for cable identification, installation standards or simply to make your wiring easier to recognise, browse our heat shrink tubing by colour:
Black Heat Shrink Tubing | Clear Heat Shrink Tubing | Red Heat Shrink Tubing | Earth Heat Shrink Tubing | White Heat Shrink Tubing | Blue Heat Shrink Tubing | Green Heat Shrink Tubing | Grey Heat Shrink Tubing | Yellow Heat Shrink Tubing | Brown Heat Shrink Tubing
For our complete selection of general-purpose, adhesive-lined, specialist and assorted heat shrink products, visit our Heat Shrink Tubing page.