Ethernet Cable Length Calculator
Calculate how much ethernet cable you need including routing overhead for walls, ceilings, and slack.
Avoid buying too little or too much.
Cable Length Needed
Ethernet cable length must account for routing — cables rarely run in a straight line from point A to point B.
Routing overhead formula:
Total Length = Straight-Line Distance + Wall Routing + Vertical Runs + Service Loops
Rules of thumb:
- Add 10–15% for routing through walls and around obstacles
- Add wall height × 2 for going up and back down between floors
- Add 6–10 feet (2–3m) of service loop at each end
- Add extra for corners — each 90° turn adds length
Maximum cable lengths (TIA/EIA-568):
| Category | Max Length | Speed |
|---|---|---|
| Cat5e | 328 ft (100m) | 1 Gbps |
| Cat6 | 328 ft (100m) | 10 Gbps (up to 164 ft) |
| Cat6a | 328 ft (100m) | 10 Gbps |
| Cat7 | 328 ft (100m) | 10 Gbps |
Cable buying tips:
- Always buy at least 10% more than calculated
- Standard pull boxes: 250 ft and 1,000 ft
- Pre-terminated cables come in 1, 3, 5, 7, 10, 15, 25, 50, 100 ft
- Bulk cable + keystone jacks = cheapest for multiple runs