Cable estimates go wrong in a specific way: someone measures the floor, multiplies by a factor they half-remember, and orders boxes. The number that actually drives the order is the outlet count, and every other line on the quote follows from it.
Start with outlets, not area
Walk the plan and count outlet positions, then modules per position. A desk is rarely one module — two is common, one for the computer and one spare or for a phone. Then add everything that is not a desk: access points, cameras, printers, displays, access control readers, the reception counter.
Write down the total number of runs. That is the number every subsequent line depends on.
Measure route length, not straight lines
A run does not travel diagonally through the air. It goes up the wall, along the tray, across the ceiling, down to the outlet. For each outlet, estimate:
- Horizontal distance from the rack, following the actual tray route
- Vertical rise at the rack end and drop at the outlet end
- Two to three metres of service loop at each end for termination and future re-work
A practical shortcut when you have a plan but not the patience: take the shortest and longest runs, average them, and multiply by the number of runs. It is close enough to order against, and it is far closer than a floor-area rule of thumb.
Add wastage
Add 10 to 15 per cent. This covers routing that turns out longer than the plan, off-cuts, re-terminations and the two runs somebody forgot. Fifteen per cent on a large job is cheaper than an emergency delivery that stops an installer for a day.
Check the 90-metre limit before ordering
No permanent link may exceed 90 metres of fixed cable, with 100 metres for the whole channel including patch cords at both ends. If any run in your estimate is over that, the answer is not longer cable — it is a switch positioned closer, or a fiber run to a secondary rack.
Finding this at ordering time costs nothing. Finding it at testing time costs a re-pull.
Convert to boxes
Cat6 is sold in 305 m boxes as standard. Divide your total by 305 and round up. Order whole boxes: part-boxes are rarely worth the negotiation, and the remainder is genuinely useful for patch runs and repairs.
Everything else follows from the run count
With the number of runs settled, the rest of the passive order is arithmetic:
- Information outlets / keystone jacks — one per run
- Face plates — one per outlet position, sized for the modules at that point
- Patch panel ports — one per run, rounded up to the next panel size, with growth
- Patch cords — two per run, one at each end
- Rack — sized from panels plus switch plus any recorder, with a manager between panel and switch
- PDU — one, sized for everything in the cabinet
This is the list sites under-order most often — not the cable, but the jacks and cords that go with it. Being ten jacks short stops work just as effectively as being a box of cable short.
A worked example
Thirty desks at two modules each, plus six access points, eight cameras, three printers and two displays: 79 runs. Average route length 35 m gives 2,765 m; add 15 per cent for 3,180 m; that is eleven 305 m boxes.
Alongside: 79 jacks, 45 face plates, a 96-port patch panel arrangement, 158 patch cords, and a rack sized for the panels and switch.
Send us the outlet count and we will quote the whole list rather than the cable alone — see Cat6 cable, jacks and patch panels and racks and cable managers.