In this guide
The maximum Ethernet cable length is 100 meters (328 feet) for the full channel, including patch cables and connectors — this applies to CAT5e, CAT6, CAT6a, and CAT7 at standard speeds.
- Total run stays at or under 100 meters (328 feet)
- You use 22–24 gauge solid copper for permanent runs
- Cable is routed away from heat sources (ambient temp near 68°F)
- Cable category matches your required speed
- Total channel length exceeds 100 meters
- You use CAT6 for 10 Gbps beyond 55 meters
- Thin 28-gauge cable is used in a long permanent run
- High ambient temperatures increase resistance beyond tolerance
Why 100 Meters Is the Limit
The 100-meter rule is set by the IEEE 802.3 Ethernet standard. Beyond this distance, signal attenuation and electrical resistance cause packet drops, reduced speeds, and higher latency. The limit covers the entire channel — your wall run plus any patch cables at each end.
Temperature plays a role too. The 328-foot figure assumes roughly 68°F ambient temperature. Warmer environments increase resistance, which effectively shortens the safe maximum length.
Speed and Category Change the Picture
Not every cable category reaches full speed at 100 meters. Here is how common categories compare:
| Setup | Works? | Need | Note |
|---|---|---|---|
| CAT5e — 100 Mbps at 100 m | Yes | CAT5e or better | Standard limit met |
| CAT6 — 1 Gbps at 100 m | Yes | CAT6 | Full distance supported |
| CAT6 — 10 Gbps at 100 m | No | CAT6a | CAT6 tops out at 55 m for 10 Gbps |
| CAT6a — 10 Gbps at 100 m | Yes | CAT6a | Full speed at full distance |
| CAT8 — 40 Gbps | Limited | CAT8 | Max 30 meters only |
Cable Gauge Matters for Long Runs
For permanent wall installations, use 22–24 gauge solid copper cable. Thinner 28-gauge cable (common in slim patch cords) reduces the safe maximum to around 315 feet — close, but short of the full standard. Always check gauge before running cable inside walls.
For more on how cable and connector type affects signal quality in other connection types, see our guide on why USB-C to HDMI stops working — many of the same signal degradation principles apply.
How to Go Beyond 100 Meters
If your run must exceed 100 meters, you have three practical options:
- Network switch: Place a switch at the 100-meter mark to regenerate the signal and start a fresh 100-meter segment.
- Ethernet extender: Uses existing copper wiring to push signals further with minimal setup.
- Fiber optic media converter: Converts to fiber for runs of hundreds of meters or more, then converts back to Ethernet at the far end.
Cisco’s overview of network switches explains how switches regenerate signals and segment your network cleanly.
If you are also connecting devices across mixed standards, check out our article on Ethernet and network cable compatibility for a broader overview.
Bottom line: Keep every Ethernet cable run under 100 meters (328 feet), use the right category for your target speed, and stick to solid copper for permanent installations. Need to go further? Add a switch or move to fiber — splitting the run is always more reliable than pushing past the limit.