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

> Cat6 horizontal cable is bought in boxes, usually of 305 m, and every run from the rack to an outlet must be one continuous length. The order therefore follows from how many whole runs fit in a box: runs per box = box length ÷ run length, rounded down, and boxes = data points ÷ runs per box, rounded up.

## 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

| Assumption | Default | Notes |
| --- | --- | --- |
| Points per cabin | 2 | Set by the IT brief |
| Points per meeting room | 2 | Add for screens and conferencing equipment |
| Points per access point | 1 | Some designs pull two |
| Service loop at the rack | 3 m | Follow the cabling specification |
| Slack at the outlet | 0.5 m | Follow the cabling specification |
| Wastage on each run | 10% | Bends, drops from the tray, dressing in the rack |
| Cable in one box | 305 m | The usual box (1,000 ft); replace with your product's data sheet |

## 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:

| Step | Calculation | Result |
| --- | --- | --- |
| Points | 120 + 8 + 6 + 6 + 8 + 2 | 150 |
| Run | (45 + 3 + 0.5) × 1.10 | 53.35 m |
| Runs per box | 305 ÷ 53.35 = 5.72, rounded down | 5 |
| Boxes | 150 ÷ 5 | 30 |
| Simple comparison | 150 × 53.35 = 8,002.5 m; ÷ 305 = 26.24, rounded up | 27 |
| Installed runs | 45 + 3.5; 80 + 3.5 | 48.5 m and 83.5 m, under 90 m |

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.

## Frequently asked questions

### How many boxes of Cat6 cable do I need?

Work out the cable for one run: route length plus slack at both ends, plus a wastage allowance. Divide the box length by that, rounding down, for the whole runs one box gives, then divide the number of points by it and round up. 150 points at a 45 m average route, with 3.5 m of slack and 10% wastage, give 53.35 m runs, 5 runs a 305 m box and 30 boxes.

### Why not just divide the total cable length by 305 m?

Because a horizontal run cannot be joined part way, so the length left in a box after the last whole run is usually wasted. In the default example the total is about 8,003 m, which divided by 305 m suggests 27 boxes, but only 5 runs fit in each box, so 30 are needed. The real figure sits between the two when long and short runs are pulled from the same box.

### What is the 90 m limit for Cat6?

ANSI/TIA-568 limits the permanent link, the fixed horizontal cable from the patch panel in the rack to the outlet, to 90 m. Patch cords at each end are extra. The calculator warns when an average or longest route plus slack goes over 90 m; the usual answer is a rack closer to the outlets, which the network designer decides.

### How much slack should I leave at each end?

A service loop at the rack lets the cable be re-terminated or moved within the rack, and a little slack at the outlet allows re-termination there. The defaults are 3 m at the rack and 0.5 m at the outlet; follow the cabling designer's or installer's specification for the project.

### Can I use it for Cat6A or other cable?

Yes. The method is the same for any horizontal cable sold in boxes or reels: enter the box or reel length from the data sheet. Cat6A cable is thicker, which affects containment fill and bend radius, but not the run count.

### Does it include patch cords, faceplates and panels?

No. It counts horizontal cable only. Patch panels, jacks, faceplates, patch cords, racks and containment are separate items, usually counted from the same list of data points.

## Sources

- [TIA-568](https://tiaonline.org/) — Commercial building telecommunications cabling — 90 m maximum horizontal cable (permanent link)

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Source: https://hagerstone.com/calculators/cat6-cable-calculator