How many network cables can each type of PVC conduit accommodate?

Customers keep asking COBTEL about running cables through PVC conduit, with the most common question being: how many network cables can you pull through a single PVC conduit?

The total cross‑sectional area of the cables inside a PVC conduit should not exceed 40% of the conduit's internal cross‑sectional area. Going over 40% makes pulling much harder-especially in buried conduit, where high resistance might prevent the cables from going through at all. If you can't fish them through and can't redo the work, the whole job is wasted.
When pulling network cable through PVC conduit, both Cat 5 and Cat 6 are used. Since Cat 5 isn't very common these days, we'll focus on Cat 5e and Cat 6, and see how many cables fit in various sizes of PVC conduit.

Cat 5e / Cat 5 conductor diameter: 0.511 mm | Cross‑sectional area: 19.625 mm² | Bounding‑square area: 25 mm²

Because cable area must stay under 40% of the conduit area, let's look at the number of cables for fill ratios of 25%, 30%, and 40%.

The calculations are precise, so some results include decimals. In practice, always round down to the nearest whole cable.

Cat 6 conductor diameter: 0.574 mm | Cross‑sectional area: 30.1754 mm² | Bounding‑square area: 38.44 mm²
Just as above, we'll check the number of cables for fill ratios of 25%, 30%, and 40%.

Note that Cat 5e and Cat 6 have different cross‑sectional areas-Cat 6 is thicker. That means, for the same conduit size, you can fit fewer Cat 6 cables than Cat 5e cables.

On real projects, besides PVC conduit, we also use PVC cable tray. The recommended fill ratio for cables in tray is 30–50%. Let's also check the capacity of common PVC trays. We'll see how many Cat 5e and Cat 6 cables fit at 30% and 50% fill.

In practice, a good target is a fill ratio around 40%-so staying between 30% and 50%.