Techflex · Sizing tool

Cable Bundle Diameter Calculator

Enter the cables going into the bundle. The calculator estimates the bundle's outside diameter and suggests a nominal sleeve size to aim for.

Cables in the bundle

Estimated bundle

–mm
Add at least one cable.
Illustrative cross-section of the cable bundle
Illustrative cross-section — not an exact packing arrangement.

Suggested sleeve size

–
Common nominal sizes, for orientation.
Nominal sizeØ mm

This is a size suggestion only. Which sleeve is right also depends on the job — abrasion resistance, heat protection, EMI shielding, flame retardancy, or whether it needs to open along its length. Sizing narrows the choice; it doesn't make it.

How the number is calculated

Identical cables, 20 or fewer. Uses the mathematically proven optimal circle-packing ratios (Graham et al.) — e.g. 7 equal cables pack into exactly 3 × one cable diameter, 19 into 4.864 ×. These are exact, not estimates.

Mixed diameters, or more than 20 cables. Uses the cross-sectional area method: D = √( Σ nᵢ·dᵢ² ÷ η ), where η is the packing efficiency set by the “bundle tightness” selector (0.85 / 0.80 / 0.72). The result is floored at the largest single cable, and at the sum of the two largest when only two cables are present.

Growth allowance multiplies the final diameter, so you can size a sleeve with room to spare.

For reference, a perfect infinite hexagonal packing has η ≈ 0.9069; real cable bundles sit well below that because the boundary is circular and cables are neither rigid nor perfectly round.

Results are for planning and reference only. Actual bundle dimensions vary with cable construction, jacket stiffness, how tightly the bundle is dressed, and installation method. Braided sleeving expands and contracts over a range, so the suggested size is a starting point — confirm against the working range of the specific sleeve before ordering. The calculator sizes the bundle; it does not select a product type.