Knowledge & service
Technical calculators for cables & tubing
Convert conductor cross-sections, compare inches and millimetres and check heat-shrink tubing dimensions geometrically.
Conductor cross-section & diameter
Geometric conversion for an ideal round solid conductor.
Equivalent solid conductor Ø
4.51 mm
This refers to the metal conductor only – without insulation and without the gaps of a stranded wire.
A = π · d² / 4 · d = √(4 · A / π)
The calculated diameter applies to the bare conductor only. To select heat-shrink tubing, the outer diameter of the cable including insulation must be measured or taken from the cable data sheet.
From dimensions to the right product.
Heat-shrink tubing in all common sizes, materials and shrink ratios.
Practical knowledge
Conductor cross-section is not cable outer diameter.
A cable rated “16 mm²” describes the metal conductor area. For an ideal round solid conductor this corresponds to a diameter of about 4.51 mm. Stranding and insulation change the actual outer diameter.
For heat-shrink, insulating and braided sleeving, use the cable data sheet or measure the component directly. Also take connectors and any other points the tubing has to pass over into account.
For tubing selection, the actual outer diameter including insulation is what counts.
How do I choose the right heat-shrink tubing size?
The expanded (supplied) inner diameter must fit over the largest point the tubing has to pass, with sufficient clearance. The maximum inner diameter after full recovery must be smaller than the smallest point to be covered. Wall thickness, material, temperature range and, if required, an adhesive lining also matter.
Why is the conductor cross-section not enough to choose the tubing?
The conductor cross-section only describes the area of the metal. For heat-shrink tubing, the actual outer diameter of the cable including insulation is what counts.
What does lay-flat width mean?
The lay-flat width is the width of the tubing when pressed flat. Ideally it equals half the circumference, i.e. roughly diameter × π / 2 for round tubing. The product data and manufacturing tolerances are decisive.
Geometric values – please also check product data and tolerances in the data sheet. All calculations run in your browser; your entries are neither stored nor transmitted.