62.5/125 vs. 50/125 Multimode Information

We have created this page to illustrate the very basic differences between 62.5 and 50/125 multimode fiber in selecting a patch cable for your existing cable plant.

The key thing to remember is to always use a patch cable of the same type as the cable that you’re connecting to. The most common installed fiber today is 62.5/125 by far. It is virtually impossible to tell the difference between the two fiber types (62.5 and 50/125) by looking at the bare fiber or the connectors. Usually, this information will be written on the cables’ jacket.

The photos above illustrate that the outer diameters of the two fiber types are the same. What is different is the size of the center light carrying core of the fiber. You cannot see the fibers’ core without a microscope. Therefore, you must rely on the writing that is on the fibers jacket to determine what type is.

Severe losses of light can occur when you try to match 50/125 and 62.5/125 fiber, as the illustration on the left shows.

NOTE: This page was designed to help you know the difference between 62.5 and 50/125 fiber for the purpose of purchasing patch cables and products to connect to existing installed cabling. This page was not designed to provide information on choosing between the two types fiber for new installations.