Cat6 Cable Calculator: Boxes of Cable for an Office Fit-Out

What it calculates

For the horizontal data cabling in a fit-out, the calculator gives:

• the total data points, from workstations, cabins, meeting rooms, access points, cameras and other outlets;
• the cable per run, with slack and wastage;
• the number of whole runs from one box;
• the boxes to order, compared with the simple total length ÷ box length;
• a warning when an installed run exceeds the 90 m permanent link in ANSI/TIA-568.

Inputs

Workstations and data points per workstation give most of the points. Cabins, meeting rooms, wireless access points, IP cameras and other points add the rest; enter 0 for any that do not apply.

Average route length is the distance from the rack to an outlet along the cable tray or trunking route, not a straight line.

Longest route is optional and is only used for the 90 m check.

The assumptions panel holds the points per cabin, meeting room and access point, the slack at the rack and outlet ends, the wastage on each run and the box length.

Method

1. Points = workstations × points each + cabins × points each + meeting rooms × points each
   • access points × points each + cameras + other points.
2. Run = (average route + rack slack + outlet slack) × (1 + wastage).
3. Runs per box = box length ÷ run, rounded down.
4. Boxes = points ÷ runs per box, rounded up.
5. For comparison: total cable = points × run, and total ÷ box length, rounded up.
6. Installed run = route + rack slack + outlet slack, checked against 90 m.

ANSI/TIA-568 limits the permanent link of horizontal cabling to 90 m. Wastage is treated as an ordering allowance and is not counted in the installed run.

Assumptions

Limitations

• Every run is taken at the average length. In practice short and long runs can be pulled from the same box, so the true number of boxes usually falls between the box-based and simple figures.
• The 90 m check uses the routes you enter. It does not know the layout; a run that is longer than the longest route entered will not be flagged.
• Backbone cabling between racks or floors, fibre, and cabling for systems such as access control or audio-visual equipment that use other cable types are not counted.
• Patch cords, panels, jacks, faceplates, racks and containment are separate items.
• Cable type and performance (category, shielding, sheath rating for the route) come from the network design, not from this calculation.

Worked example

An office with 60 workstations at 2 points each, 4 cabins and 3 meeting rooms at 2 points each, 6 access points, 8 IP cameras and 2 other points, a 45 m average route, an 80 m longest route, 3 m and 0.5 m of slack, 10% wastage and 305 m boxes:

The office needs 30 boxes of 305 m, not the 27 that total length alone suggests, and about 1,148 m is left in box ends. No warning is shown, as the longest installed run is 83.5 m. At a 60 m average route the run becomes 69.85 m, only 4 fit in a box, and the order rises to 38 boxes.

How engineers use it

On a fit-out, the IT brief and furniture layout set the data points, and the cabling designer places racks so every outlet is within the permanent link limit. The installer then prepares a cable schedule with the route length of each run, groups runs by box so long and short pulls share a box, and orders from that schedule. Containment is sized for the cable count and future growth.

When a professional design must replace it

Use the calculator for an early estimate or to check a cabling quotation. Replace it with a cabling design and cable schedule before ordering, and wherever the layout has more than one rack location, long routes near the 90 m limit, cabling through a raised floor or ceiling void with its own requirements, or a network that must be tested and documented to a specific standard. The network designer decides the cable category, rack positions and test requirements.