Helixal — Professional Heat Shrink Tubing
Helixal — Professional Heat Shrink Tubing
Enter your wire gauge (AWG), a measured diameter in inches or mm, or the width and height of a rectangular part like a connector body or bus bar. Select the shrink ratio — 2:1, 3:1, or 4:1 — and see every compatible standard heat shrink size with the pre-shrink expanded ID, post-shrink recovered ID, and a best-fit recommendation. No registration, no download. Covers 3/32” to 6” expanded ID.
| Size | Expanded ID | Shrunk ÷3 | Grip |
|---|---|---|---|
| 5/8" | 15.9 mm | 5.3 mm | ✓ grips |
| 3/4" | 19.1 mm | 6.4 mm | ✓ grips |
| 1" | 25.4 mm | 8.5 mm | ✓ grips |
| 1-1/4" | 31.8 mm | 10.6 mm | ✓ grips |
| 1-1/2" | 38.1 mm | 12.7 mm | loose |
| 2" | 50.8 mm | 16.9 mm | loose |
| 2-1/2" | 63.5 mm | 21.2 mm | loose |
| 3" | 76.2 mm | 25.4 mm | loose |
| 4" | 101.6 mm | 33.9 mm | loose |
| 6" | 152.4 mm | 50.8 mm | loose |
Rule: expanded ≥ object × 1.1 · recovered = expanded ÷ 3
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Get the embed code →Core Formula
Recovered ID = Expanded ID ÷ Shrink Ratio
Example (3:1): 6.4 mm ÷ 3 = 2.1 mm recovered ID
Heat shrink tubing is always sized by its expanded (pre-shrink) inner diameter — the diameter before heat is applied. When heated, the tubing shrinks radially by the rated ratio. A 3:1 tube with a 9.5 mm expanded ID will recover to 9.5 ÷ 3 = 3.2 mm inner diameter.
For the tubing to slide over your wire or connector, the expanded ID must be at least 10% larger than the object outer diameter. This is the minimum clearance that allows easy installation without forcing the tubing. For sharp connector edges or irregular profiles, use 15–20% clearance.
For the tubing to grip after shrinking, the recovered ID must be smaller than the object outer diameter. If the recovered ID is larger than or equal to the object OD, the tubing will shrink against the surface but not constrict around it — the fit will be loose. In that case, either switch to a higher ratio (2:1 → 3:1 → 4:1) or size down one increment.
The calculator above applies these rules automatically and marks results as GRIPS (recovered ID < object OD) or LOOSE (recovered ID ≥ object OD) for each compatible size.
Shrink ratio determines how much the tubing contracts in diameter. Higher ratios provide more recovery — which means you can cover a wider range of object sizes and get a tighter grip on smaller diameters.
2:1
Shrinks to 50% of original diameter
Wall Type
Single wall, no adhesive
Best For
Basic electrical insulation, colour coding, abrasion protection on uniform-diameter wire. Best when the wire OD is close to the expanded ID.
Example
1/2" (12.7 mm) tubing → 6.4 mm recovered
3:1
Shrinks to 33% of original diameter
Wall Type
Dual wall with adhesive inner layer (standard for marine/auto)
Best For
Waterproof butt splices, crimp connectors, battery terminal insulation, marine wiring, automotive harnesses. The 3:1 ratio covers wide connector-to-wire transitions in a single piece.
Example
1/2" (12.7 mm) tubing → 4.2 mm recovered
4:1
Shrinks to 25% of original diameter
Wall Type
Single or dual wall depending on manufacturer and spec
Best For
Large connector bodies, MIL-spec cable assemblies, battery lug insulation on large conductors (4/0–500 MCM), cable jacket repair, high-ratio transitions from thick to thin profiles.
Example
1/2" (12.7 mm) tubing → 3.2 mm recovered
Recommended heat shrink tubing size for each AWG wire gauge. The bare conductor diameters are listed for reference, but the recommendation sizes for typical insulated wire of that gauge — which is what you actually sleeve. If you have measured the real outer diameter of your wire or connector, enter it directly in the calculator above instead.
This chart sizes tubing to bare conductor. If you are sealing a crimped butt splice, ring terminal, or lug — which is most repair work — size to the barrel OD instead, because that is the widest point the tube must pass over. Sizing to the wire alone gives you a tube that will not slide over the connector.
Measure the barrel with calipers, allow roughly 20% clearance so the tube slides on cold, then confirm the recovered diameter is smaller than the narrowest thing it must grip. Over a crimp in automotive, marine, or outdoor work, use 3:1 adhesive-lined dual wall — single-wall tubing lets water wick along the strands.
| Wire Gauge | Bare Conductor OD (mm) | Bare Conductor OD (in) | 2:1 Size (insulated wire) | 3:1 Size (insulated wire) |
|---|---|---|---|---|
| 28 AWG | 0.33 mm | 0.013” | 3/32" | 3/32" |
| 26 AWG | 0.41 mm | 0.016” | 3/32" | 3/32" |
| 24 AWG | 0.51 mm | 0.020” | 3/32" | 3/32" |
| 22 AWG | 0.64 mm | 0.025” | 3/32" | 3/32" |
| 20 AWG | 0.81 mm | 0.032” | 1/8" | 3/32" |
| 18 AWG | 1.02 mm | 0.040” | 1/8" | 1/8" |
| 16 AWG | 1.29 mm | 0.051” | 3/16" | 1/8" |
| 14 AWG | 1.63 mm | 0.064” | 3/16" | 3/16" |
| 12 AWG | 2.05 mm | 0.081” | 1/4" | 1/4" |
| 10 AWG | 2.59 mm | 0.102” | 5/16" | 1/4" |
| 8 AWG | 3.26 mm | 0.128” | 3/8" | 5/16" |
| 6 AWG | 4.11 mm | 0.162” | 1/2" | 3/8" |
| 4 AWG | 5.19 mm | 0.204” | 5/8" | 1/2" |
| 2 AWG | 6.54 mm | 0.258” | 3/4" | 5/8" |
| 1 AWG | 7.35 mm | 0.289” | 3/4" | 5/8" |
| 1/0 AWG | 8.25 mm | 0.325” | 1" | 3/4" |
| 2/0 AWG | 9.27 mm | 0.365” | 1" | 3/4" |
| 3/0 AWG | 10.4 mm | 0.410” | 1-1/4" | 1" |
| 4/0 AWG | 11.68 mm | 0.460” | 1-1/4" | 1" |
| 250 MCM | 13.41 mm | 0.528” | 1-1/2" | 1-1/4" |
| 350 MCM | 15.78 mm | 0.621” | 2" | 1-1/2" |
| 500 MCM | 18.9 mm | 0.745” | 2" | 2" |
Conductor OD values per ASTM B3 / B8 solid and stranded copper. For multi-conductor cables, measure the bundle OD or jacket OD directly with calipers.
Size heat shrink to the crimp barrel OD — not the wire. Insulated barrel for 22–18 AWG: ~5–6 mm → use 1/4" (6.4 mm) 3:1 dual-wall. For 16–14 AWG barrels (~7–8 mm): use 3/8" (9.5 mm). For 12–10 AWG barrels (~9–11 mm): use 1/2" (12.7 mm). Always use 3:1 adhesive-lined tubing over crimp splices for waterproof marine, automotive, and outdoor work. The adhesive flows past the crimp barrel edges for a hermetic seal.
Recommended ratio: 3:1 Dual WallFor ring lugs and cable end terminals, measure the barrel OD of the lug. A 4 AWG lug barrel is typically 8–9 mm — use 3/4" (19.1 mm) or 1" (25.4 mm) 3:1 to cover the barrel and transition onto the cable insulation. For 2/0 and larger cables with big lug barrels, 4:1 heat shrink covers both the lug body and the smaller cable jacket in a single piece without needing two sizes. ABYC E-11 requires all battery connections to be insulated and protected from accidental short-circuit.
Recommended ratio: 3:1 or 4:1ABYC E-11 Table XI wire sizing applies to all marine electrical work. For below-deck splices, every connection must be waterproof — 3:1 dual-wall adhesive-lined heat shrink is the standard. Use tinned copper wire and 3:1 heat shrink over all butt splices, ring terminal barrels, and inline connections. Size the heat shrink to the crimp barrel or connector body OD, not the wire OD. Allow 12–20 mm of overlap past each connection edge to ensure the adhesive creates a seal beyond the splice point.
Recommended ratio: 3:1 Dual WallFor multi-conductor cable bundles and industrial harnesses, measure the bundle OD after bundling. For strain relief at cable entry points, use 2:1 or 3:1 heat shrink sized to the outer jacket or conduit connector OD. For environmental sealing on panel entry grommets, 3:1 adhesive-lined is preferred — the adhesive fills gaps between jacket and fitting. For large-diameter industrial cables (250–500 MCM), 4:1 tubing in 2"–4" sizes provides reliable insulation on cable splices and lug connections rated for heavy industrial current.
Recommended ratio: 2:1 or 3:1Measure the outer diameter (OD) of the wire, connector, or object you are sleeving. Choose a heat shrink size whose expanded (pre-shrink) inner diameter is at least 10–20% larger than that measurement — so the tubing slides on freely. The recovered (post-shrink) inner diameter must be smaller than the object OD for a tight grip. Formula: Recovered ID = Expanded ID ÷ Shrink Ratio. For 3:1 tubing with a 6.4 mm expanded ID, the recovered ID = 6.4 ÷ 3 = 2.1 mm.
The core formula is: Recovered ID = Expanded ID ÷ Shrink Ratio. For 2:1 tubing, recovered ID = expanded ID ÷ 2. For 3:1 tubing, recovered ID = expanded ID ÷ 3. For 4:1 tubing, recovered ID = expanded ID ÷ 4. To size correctly: (1) measure your object OD, (2) multiply by 1.1–1.2 to get the minimum expanded ID you need, (3) select the smallest available heat shrink size above that minimum, (4) verify the recovered ID is smaller than your object OD for a grip.
2:1 heat shrink shrinks to half its original diameter — used for basic insulation and strain relief where the object diameter is close to the tubing diameter. 3:1 heat shrink shrinks to one-third of its original diameter — the most versatile ratio, standard for connectors, butt splices, and waterproof applications. 3:1 dual-wall adhesive-lined tubing provides a watertight seal. 4:1 heat shrink shrinks to one-quarter of its original diameter — used for large connector bodies, cable repair over non-uniform shapes, and high-ratio transitions where a single tube needs to cover both a thick connector and a thin wire exit.
The standard minimum clearance is 10% — the expanded inner diameter should be at least 10% larger than the object OD so the tubing slides on without forcing. For connectors with sharp edges or uneven profiles, 15–20% clearance is recommended. Too little clearance risks tearing the tubing during installation. Too much clearance (more than 50% oversize on 2:1 tubing) can result in incomplete shrink and loose coverage, especially on very thin wire.
Use 1/4" (6.4 mm) heat shrink for 12 AWG wire, at either 2:1 or 3:1. Insulated 12 AWG THHN measures roughly 4.5 mm across the jacket, so the 6.4 mm expanded ID slides on with comfortable clearance and recovers to 2.1 mm at 3:1 for a firm grip. The bare conductor is 2.05 mm (0.081"), but you almost never sleeve bare copper — size to the insulated OD. Over a crimped 12 AWG butt splice the barrel measures 9–11 mm, which needs 1/2" (12.7 mm) 3:1 dual-wall instead.
Use 3/16" (4.8 mm) heat shrink for 14 AWG wire, at either 2:1 or 3:1. Insulated 14 AWG is typically about 3.5 mm over the jacket, so the 4.8 mm expanded ID slides on with room to spare and recovers to 1.6 mm at 3:1. The bare conductor measures 1.63 mm (0.064"), but the insulated outer diameter is what the tubing must clear. Over a crimped 14 AWG splice, size to the barrel — usually 7–8 mm — and use 3/8" (9.5 mm) 3:1 adhesive-lined.
Use 5/16" (7.9 mm) for 2:1 heat shrink on 10 AWG wire, or 1/4" (6.4 mm) for 3:1. Insulated 10 AWG runs about 5.5 mm over the jacket, and the higher 3:1 recovery lets the smaller 1/4" size still close down firmly on it. The bare conductor is 2.59 mm (0.102"), but sizing to bare copper leaves you with tubing that will not pass over the insulation at all. For 10 AWG crimp barrels (9–11 mm) step up to 1/2" (12.7 mm), and for a multi-strand bundle measure the actual bundle OD and add 10–20%.
Use 3/32" (2.4 mm) heat shrink for 22 AWG wire at both 2:1 and 3:1. Insulated 22 AWG hookup wire is roughly 1.7 mm over the jacket, so the 2.4 mm expanded ID slides on easily and still recovers tight around it. The bare conductor is only 0.64 mm (0.025"). For a crimped 22 AWG butt splice the barrel runs 5–6 mm, which needs 1/4" (6.4 mm) 3:1 adhesive-lined instead.
Use 1/8" (3.2 mm) for 2:1 heat shrink on 20 AWG wire, or 3/32" (2.4 mm) for 3:1. Insulated 20 AWG is about 2.0 mm over the jacket, and the greater 3:1 recovery lets the smaller 3/32" size grip it properly where 2:1 needs the extra room. The bare conductor measures 0.81 mm (0.032"). Over a crimped 20 AWG splice, size to the 5–6 mm barrel and use 1/4" (6.4 mm) 3:1 dual-wall.
Use 1/8" (3.2 mm) heat shrink for 18 AWG wire at both 2:1 and 3:1. Insulated 18 AWG — the common automotive and signal size — measures roughly 2.4 mm over the jacket, which the 3.2 mm expanded ID clears comfortably while still recovering tight. The bare conductor is 1.02 mm (0.040"). For a crimped 18 AWG butt splice, size to the 5–6 mm barrel and use 1/4" (6.4 mm) 3:1 adhesive-lined.
Use 3/16" (4.8 mm) for 2:1 heat shrink on 16 AWG wire, or 1/8" (3.2 mm) for 3:1. Insulated 16 AWG measures about 2.8 mm across the jacket — the 3:1 ratio recovers hard enough that the smaller 1/8" size still grips it, while 2:1 needs the extra room of 3/16". The bare conductor is only 1.29 mm (0.051"), but the tubing has to pass over the insulation, not the copper, so size to the jacket. If you are covering a crimped 16 AWG butt splice, size to the barrel instead — those run 7–8 mm — and use 3/8" (9.5 mm) 3:1 adhesive-lined.
Use 3/8" (9.5 mm) for 2:1 heat shrink on 8 AWG wire, or 5/16" (7.9 mm) for 3:1. Insulated 8 AWG — common in battery and inverter runs — measures roughly 7 mm over the jacket, and the 3:1 recovery closes the smaller 5/16" size down onto it securely. The bare conductor is 3.26 mm (0.128"). For 8 AWG ring terminals and lugs, size to the barrel rather than the cable, since the barrel is the widest point the tube must pass over.
Use 1/2" (12.7 mm) for 2:1 heat shrink on 6 AWG wire, or 3/8" (9.5 mm) for 3:1. Insulated 6 AWG measures about 8.5 mm over the jacket, so the 3:1 recovery of the 3/8" size grips it firmly while still sliding on cold. The bare conductor is 4.11 mm (0.162"). For 6 AWG battery and marine lugs, size to the lug barrel instead — often 3/4" (19.1 mm) or larger.
Use 5/8" (15.9 mm) for 2:1 heat shrink on 4 AWG wire, or 1/2" (12.7 mm) for 3:1. Insulated 4 AWG cable is roughly 10.5 mm over the jacket, and 1/2" 3:1 adhesive-lined is the standard choice for a waterproof seal on 4 AWG battery and inverter runs. The bare conductor is 5.19 mm (0.204"). When you are covering the lug itself rather than the cable, size to the barrel and palm — 3/4" (19.1 mm) is typical.
Use 3/4" (19.1 mm) for 2:1 heat shrink on 2 AWG wire, or 5/8" (15.9 mm) for 3:1. Insulated 2 AWG cable measures about 13 mm over the jacket, and 5/8" 3:1 adhesive-lined is the standard seal for 2 AWG battery cable. The bare conductor is 6.54 mm (0.258"). A 2 AWG lug barrel plus palm exceeds 15 mm, so if you are covering the terminal itself step up to 1" (25.4 mm).
Use 1-1/4" (31.8 mm) for 2:1 heat shrink on 4/0 cable, or 1" (25.4 mm) for 3:1. Insulated 4/0 welding and battery cable measures roughly 23 mm over the jacket, which the 25.4 mm expanded ID clears. 3:1 adhesive-lined at 1" is standard for waterproof seals on 4/0 runs. The bare conductor is 11.68 mm (0.460"). For the lug barrel itself, step up to 1-1/2" (38.1 mm).
Size the heat shrink to the crimp barrel OD, not the wire. Insulated butt splice barrels for 22–18 AWG measure 5–6 mm — use 1/4" (6.4 mm) dual-wall 3:1. For 16–14 AWG barrels (7–8 mm) use 3/8" (9.5 mm). For 12–10 AWG barrels (9–11 mm) use 1/2" (12.7 mm). Always use 3:1 adhesive-lined (dual wall) heat shrink over crimp splices in automotive, marine, and outdoor applications to achieve a waterproof seal.
Yes — 3:1 heat shrink can replace 2:1 in virtually all applications where the expanded ID still slides over the object. The higher shrink ratio gives you more recovery, which means the tubing will grip more aggressively and cover a wider range of object sizes. The only case where 2:1 is preferred over 3:1 is when you specifically want a lighter, thinner-walled sleeve for basic insulation on uniform wire, where adhesive sealing is not needed and minimum wall thickness matters.
4:1 heat shrink tubing has the highest shrink ratio and is used for: (1) large connector bodies where the connector barrel is significantly wider than the wire exit, (2) battery lug insulation where the lug OD is much larger than the cable OD, (3) cable repair and re-jacketing over damaged insulation, (4) hose protection where a large bore needs to transition to a smaller connection, and (5) any application requiring a single piece of heat shrink to cover a wide diameter transition. It is common in military, aerospace, and subsea cabling.
Yes — heat shrink tubing shrinks both radially (in diameter, by the rated ratio) and longitudinally (lengthwise, typically 5–10% depending on the material and manufacturer). To account for this, cut your piece 10–15% longer than the area you need to cover, and ensure the tubing overlaps beyond your connection or splice on both ends. For dual-wall adhesive-lined tubing, the overlap also ensures the adhesive flows past the connection edges for a complete environmental seal.
Standard heat shrink tubing ranges from 3/32" (2.4 mm) expanded ID at the small end up to 6", 8", or even larger in specialty rolls. Common stock sizes are 3/32", 1/8", 3/16", 1/4", 5/16", 3/8", 1/2", 5/8", 3/4", 1", 1-1/4", 1-1/2", 2", 3", 4", and 6" expanded ID. Very small sizes below 3/32" exist in specialty electronics packaging. Very large sizes above 6" are used in industrial pipeline and cable insulation. The calculator above covers the full standard industrial range from 2.4 mm to 152 mm expanded ID.
Helixal stocks 2:1 and 3:1 dual-wall heat shrink in 13 sizes — 3/32” to 2”.
UL 224 · RoHS · Ships direct from USA in 1–3 business days.
Want the full reference? See the heat shrink size chart & AWG guide.