Heat Shrink Tubing Size Chart: What Size Do I Need? (Single & Dual Wall)

October 06, 2026

To size heat shrink tubing, measure the widest point it has to slide over and the narrowest point it has to grip. Choose tubing whose expanded (as-supplied) inside diameter is about 20–30% larger than the widest point, and whose fully recovered diameter is smaller than the narrowest point. Single wall tubing shrinks 2:1; adhesive-lined dual wall tubing shrinks 3:1 and seals out water. The charts below give the exact expanded and recovered diameters for every size we stock, and which of our wire gauges each one fits.

How Heat Shrink Sizes Work

Heat shrink is sold by its expanded inside diameter — the size before you heat it. The shrink ratio tells you how small it gets: 2:1 tubing recovers to half its supplied size, 3:1 tubing to one third. A 3/8" single wall tube (2:1) recovers to 3/16"; a 3/8" dual wall tube (3:1) recovers to 1/8".

The tube only grips if the recovered diameter is smaller than the part underneath, so the usable range for any size runs from its recovered diameter up to a little under its expanded diameter. That is why a higher ratio covers a wider range — and why 3:1 dual wall is the easier choice when the tube has to pass over a connector or lug and then tighten onto much thinner wire.

Single Wall Heat Shrink Size Chart (2:1)

UL Listed and CSA certified flame-retardant polyolefin, rated -55°C to 125°C, shrinks at 90–120°C. Stocked in black, red, blue, clear and white, in 6 in and 4 ft lengths (bulk spools on most sizes). Use it for insulation, strain relief, bundling and color-coding in dry locations — it is not waterproof.

Dual Wall Adhesive-Lined Heat Shrink Size Chart (3:1)

UL Listed and CSA certified polyolefin with an inner adhesive layer that melts as the tube shrinks and seals the joint watertight. Rated -45°C to 125°C; begins shrinking at about 100°C. Stocked in black and red, in 6 in and 4 ft lengths. Use it on splices, terminals and lugs on boats, trailers, engine bays and anywhere the connection can get wet.

*Based on the nominal outside diameter of our GPT primary wire (18–10 AWG) and battery cable (8 AWG–2/0), leaving 20% clearance to slide the tube on. Other brands and insulation types (THHN, cross-linked, marine) have different diameters — measure your wire if it isn't ours.

Quick Lookup: What Size Heat Shrink for My Wire?

Covering wire alone — for example, a nick in the insulation or bundling a lead. If the tube must pass over a connector, butt splice or lug first, size it from that part instead (see below).

Sizing Over Splices, Terminals and Lugs

1. Measure the widest point the tube must slide over — usually the crimp barrel of a butt connector, ring terminal or lug.
2. Measure the narrowest point it must grip — usually the wire insulation on each side.
3. Pick a size whose expanded diameter is 20–30% larger than the widest point and whose recovered diameter is smaller than the narrowest point. If no 2:1 size covers both, use 3:1 dual wall.
4. Cut it long enough to extend past the joint onto the insulation on both sides. Heat shrink also gets slightly shorter as it shrinks (typically a few percent), so cut a little extra.

Example: a 2 AWG battery cable (0.430") with a tinned copper lug. The lug barrel is the widest point; 1" dual wall (3:1) slides over it and recovers to 0.333", tight on the 0.430" cable. For lugs and battery terminals that see water, dual wall is the better choice because the adhesive seals the end of the barrel.

If you would rather skip separate tubing on small-gauge splices and terminals, heat shrink butt connectors and heat shrink ring terminals come with the adhesive-lined sleeve already attached, color-coded red (22–18 AWG), blue (16–14 AWG) and yellow (12–10 AWG).

Single Wall vs Dual Wall: Which Do You Need?

How to Shrink It Properly

1. Slide the tubing onto the wire before you crimp or solder the connection.
2. Center it over the joint.
3. Use a heat gun and keep it moving. Start in the middle and work toward the ends so air is pushed out, not trapped.
4. Dual wall: stop when the tube is tight all round and a small bead of adhesive appears at each end.
5. Let it cool before you flex the wire.

A lighter or torch can work in a pinch but scorches tubing easily and heats unevenly; a heat gun gives a cleaner, more reliable seal.

Frequently Asked Questions

What size heat shrink do I need for 12 AWG wire?

For our 12 AWG GPT wire (0.142" OD) on its own, 3/16" or 1/4" single wall, or 1/4" dual wall. Over a 12–10 AWG butt splice or terminal barrel, size up to fit the barrel — 3/8" dual wall is a common choice.

What size heat shrink for 10 AWG wire?

Our 10 AWG wire is 0.174" OD: 1/4" single wall or 1/4"–3/8" dual wall on the wire itself.

What size heat shrink for 2/0 battery cable?

Our 2/0 cable is 0.605" OD. Use 3/4" or 1" single wall, or 3/4"–1-1/2" dual wall. Over a lug, 1" or 1-1/2" dual wall lets the tube pass the barrel and still grip the cable.

Is heat shrink tubing waterproof?

Only adhesive-lined (dual wall) tubing seals out water. Single wall insulates and protects but water can wick in at the ends.

What does 2:1 or 3:1 mean?

The shrink ratio: 2:1 tubing shrinks to half its supplied diameter, 3:1 to one third.

Does heat shrink get shorter when you heat it?

Slightly — typically a few percent of its length. Cut a little longer than the joint.

Can you reuse heat shrink?

No. Once recovered it will not expand again; cut it off and replace it.

Related Guides and Products

• Ring terminal size chart — wire gauge, stud size and color code
• Wire gauge calculator — pick the right gauge for your amps and run length
• Heat shrink tubing guide — materials, types and installation
• All heat shrink tubing
• Split loom and spiral wrap for protecting whole harnesses

Also in News