How does the length of an Ethernet cable influence internet speed?

stuart January 18, 2011

How much speed would I lose using 80m of Ethernet cable? I have 3mgb.

  1. Oron Joffe
    January 20, 2011 at 11:18 pm

    Agree with Mike. To all intents and purposes, there is no speed loss up to 100m (and even beyond). If there is a lot of electrical noise on the way, use a shielded cable, but I have to say I've NEVER had to do that.

  2. Mike
    January 19, 2011 at 1:23 am

    In theory, for 100 meters (maximum length for Twisted-Pair cables) the speed loss is around 0.3 percent duo to higher latency.

    In real world application it depends on any and all sources of interference in between.
    Using screened and/or foiled Cat5e cable there should be no problem running Gigabit Ethernet in your home environment for cables up to 100 meters.

    If you plan to pass it by your microwave you should probably get an S/FTP (screened AND foiled) cable and pray to the IT-God :)

  3. Anonymous
    January 18, 2011 at 7:18 pm


    Cable quality can have alot to do with speeds. If the connection is still slow, it probably is the network cable, otherwise there is something misconfigured on the desktop or router. But sometimes it can be more important to have a connection than have a high speed connection. For example 10Mbps can be far enough to share an internet connection.

    List of Ethernet standards

    Maximum cable lengh for ethernet depends on what kind of ethernet you are talking about
    Gigabit Ethernet (over copper), 1000baseT
    Speed: 1000 Mbps
    Max Len: 100 Meters
    Cable: UTP, RJ-45 connectors

    Fast Ethernet, 100baseT
    Speed: 100 Mbps
    Max Len: 100 Meters
    Cable: UTP, RJ-45 connectors

    Twisted Pair Ethernet, 10baseT
    Speed: 10 Mbps
    Max Len: 100 Meters
    Cable: UTP, RJ-45 connectors

    Thin Ethernet , 10 base 2
    Speed: 10 Mbps
    Max Len: 185 Meters
    Cable: RG-58 type coax, 50 ohm impedance

    Thick Ethernet, 10 base 5
    Speed: 10 Mbps
    Max Len: 500 Meters
    Cable: RG-58 type coax, 50 ohm impedance

    Ethernet to Fiber media converters are starting to come down in price - they can be found for under $150. When 100Meters is not enough distance, an Ethernet to fiber media converter can be placed on each end making the maximum distance something like 40Km. Another use for fiber is electrical insulation. Some people like to run cables underground between homes. If you run CAT5 cable, the homes have different 'ground potentials' and you will burn out network card durring any electrical storm. The solution is fiber! Run fiber betweeen the homes or run a pair of fiber converters on one end of the cable with a short fiber run. This will electrically separate the two homes.

    Cable specifications for the 10-Mbps 10BaseT cable with RJ-45 connector:
    Category 3 or Category 5 UTP with 22 to 24 AWG
    Maximum segment length ..... 100 m (328 ft.) for 10BaseT
    Maximum network length ....2,800 m (9,186 ft.) (with four repeaters)

    Cable specifications and connection limits for 100-Mbps transmission, RJ-45 connector.
    Category 5, UTP, 22 to 24 AWG
    Maximum segment length .... 100m (328 ft.) for 100BaseTX
    Maximum network length .... 200 m (656 ft.) (with one repeater)