Containment type & size
Cable mix - enter quantities
| Cable type | OD (mm) | Qty | Total area |
|---|
Fill guidance (editable)
Cable area breakdown
| Cable | OD | Qty | Area |
|---|---|---|---|
| Total cable area | 0 mm² | ||
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ACCL specifies conduit, trunking and tray sizing as part of every infrastructure design - free on all survey and quotation projects.
0333 900 0101How this cable fill calculator works
Use the cable fill calculator to compare a mixed cable schedule with the usable cross-sectional area of conduit, trunking or cable tray. Select the containment type and dimensions, enter the quantity and outside diameter of each cable, and the result updates instantly.
The calculation uses the outside diameter of each circular cable to estimate its occupied area. Because cable diameters vary by manufacturer and product construction, confirm the figures against the selected cable datasheet before finalising a structured data cabling design.
The calculator supports copper data cables, coax and fibre, as well as custom cable types. This makes it useful for early route planning across office fit-outs, comms-room upgrades, security systems and fibre optic installations.
Important: the default fill percentages are editable planning values, not universal legal limits. Final containment sizing should follow the project specification, current installation standards, manufacturer data and the practical route conditions found during survey.
Why cable containment capacity matters
Overfilled conduit or trunking can increase pulling tension, compress cable bundles, make bend-radius control more difficult and leave no practical capacity for future additions. ACCL’s guide to common data cabling faults explains how overfilled containment can also contribute to damaged links and thermal problems on high-density PoE installations.
Containment should be selected around the complete cable schedule, route length, bends, draw-in points, segregation, fire stopping, manufacturer dimensions and future growth. Our office cabling service includes trunking, containment and above-ceiling or under-floor routing as part of the installation design.
For mixed copper and fibre routes, consider cable outside diameter, bend requirements and how the pathway will be accessed later. The cable category itself also affects diameter, shielding and bundle density, so review our comparison of Cat5e, Cat6, Cat6A, Cat7 and Cat8 cables when building the schedule.
The wider planning and installation principles for telecommunications pathways are covered by ISO/IEC 14763-2:2019 and, for cabling inside buildings, BS EN 50174-2:2018.
A calculation cannot confirm the actual route, internal product dimensions, existing services or installation access. ACCL’s free site survey checks these conditions before a containment design and fixed-price quotation are prepared.
Need the containment design checked?
Book a free ACCL site survey to confirm cable quantities, pathway dimensions, route constraints, future capacity and the correct conduit, trunking or tray specification.
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Have a no-obligation chat with one of our data cabling experts, who can recommend a solution to suit your requirements and budget.
Frequently Asked Questions – (FAQs)
Q. What is cable fill?
Cable fill is the proportion of the usable internal area of a conduit, trunking or cable tray that is occupied by cables. Leaving sufficient unused capacity helps with installation, cable management and future additions.
Q. How does the cable fill calculator work?
The calculator uses the outside diameter and quantity of each cable to estimate its cross-sectional area. It then compares the combined cable area with the internal area of the selected containment.
Q. What cable fill percentage should I use?
There is no single percentage that applies to every pathway or project. The calculator provides editable planning values, but the final allowance should follow the project specification, current installation standards, manufacturer guidance and actual site conditions.
Q. Why should containment have spare capacity?
Spare capacity makes cables easier to install and maintain, provides room for future additions and reduces the risk of excessive pulling pressure, compressed bundles and poor thermal performance.
Q. Can I calculate a mixture of different cable types?
Yes. You can combine Cat5e, Cat6, Cat6A, Cat7, fibre and coax cables or add a custom cable using its measured outside diameter.
Q. Why is the cable outside diameter important?
Cables within the same category can have different outside diameters because of conductor size, shielding, jacket construction and manufacturer design. Using the selected product’s actual diameter produces a more reliable result.
Q. Can overfilled containment affect PoE cabling?
Dense cable bundles can retain more heat, particularly where multiple cables carry higher PoE loads. Cable category, conductor size, bundle arrangement, ambient temperature and containment design should all be considered.
Q. Do I still need a site survey?
Yes. The calculator cannot assess bends, draw-in points, segregation, fire stopping, existing services, route access or the exact internal dimensions of the selected containment. A site survey is required before the final design is confirmed.