For most home and office networks, the practical reach of a standard Ethernet cable stops at 100 meters (328 feet). This limit, set by the official networking standard known as TIA/EIA, applies to common twisted-pair cables like Cat5e, Cat6, and Cat6a. Beyond this distance, the electrical signal begins to fade, causing data loss, slower speeds, and unstable connections. Therefore, for a direct run from a router to a computer or a switch to a security camera, 100 meters is your golden rule.
How long can you run Ethernet without major tricks? Exactly 100 meters for a single, reliable, full-speed connection. However, this distance includes both the main cable and the How long can you run Ethernet shorter patch cords at each end. If you need to go further, you have options: insert a network switch every 100 meters to regenerate the signal, use a Power over Ethernet (PoE) extender, or switch to fiber optic cable, which can run kilometers. For most DIY projects, sticking under 100 meters ensures you avoid weird glitches and slow performance.
Pushing Past the Limit
If you ignore the limit and run Ethernet longer than 100 meters, the results are unpredictable. At 120 meters, you might see your speed drop from 1 Gbps to 100 Mbps. At 150 meters, connections may disconnect randomly. For critical setups like office networks or security systems, staying within 100 meters is not a suggestion—it is a requirement. When in doubt, measure your cable path twice, add a switch halfway, or choose fiber for truly long distances. Your network’s health depends on respecting that invisible line.