Comparison Between OM1, OM2, OM3 and OM4

Multimode fibers are identified by the OM (optical mode) designation as outlined in the ISO/IEC 11801 standard. Multimode fiber cables can be found in OM1, OM2, OM3 and OM4 types. Each type has different properties. This post will reveal a comparison between the four different multimode fibers.

development of multimode fibers

Parameters & Specification

The original multimode fiber (MMF) standard ANSI/TIA-492AAAA5 for OM1 fiber, was released in 1989 to support Fast Ethernet 100BASE-FX and 1000BASE-SX Ethernet. It’s a kind of multimode fiber with 200/500 overfilled launch (OFL) bandwidth at 850/1300nm.

The ANSI/TIA-492AAAB standard for OM2 fiber was released in 1998, with an improved modal bandwidth to support higher data transmission, such as 1 Gbps VCSEL with longer reach. It’s a kind of multimode fiber with 500/500 OFL bandwidth at 850/1300nm.

To meet growing bandwidth requirements, laser-optimized multimode fiber (LOMMF) standards OM3 and OM4 fiber cable were developed in 2002 and 2009 respectively. OM3 cable refers to laser-optimized 50µm fiber having 2000 effective modal bandwidth (EMB, also known as laser bandwidth) designed for 10 Gb/s transmission. OM4 cable means laser-optimized 50µm fiber having 4700 EMB bandwidth designed for 10 Gb/s, 40 Gb/s, and 100 Gb/s transmission.


Design & Application

OM1 cable typically comes with an orange jacket and has a core size of 62.5 micrometers (µm). It can support 100 Megabit Ethernet at lengths up 33 meters. It is most commonly used for 100 Megabit Ethernet applications.

OM2 fiber also has a suggested jacket color of orange. Its core size is 50µm, smaller than OM1 fiber. It supports 1 Gigabit Ethernet at lengths up to 82 meters but is more commonly used for 1 Gigabit Ethernet applications. Both OM1 and OM2 work well with LED based equipment that can send hundreds of modes of light down the cable. And for yeas they have been widely deployed in the interior of the building.

OM3 multimode fiber has a suggested jacket color of aqua. Like OM2, its core size is 50µm, but the cable is optimized for laser based equipment that uses fewer modes of light. As a result of this optimization, it is capable of running 10 Gigabit Ethernet at lengths up to 300 meters. Besides, OM3 cable is able to support 40 Gigabit and 100 Gigabit Ethernet up to 100 meters if a MPO connector is utilized. 10 Gigabit Ethernet is its most common use.

OM4 fiber also has a suggested jacket color of aqua. It is a further improvement to OM3. It also uses a 50µm core but it supports 10 Gigabit Ethernet at lengths up 550 meters and it supports 100 Gigabit Ethernet at lengths up to 150 meters utilizing a MPO connector. Generally, OM3 and OM4 fiber optic cables are typically used in the data center wiring environment to support the transmission of 10G, even the 40/100G high speed Ethernet network.



OM1 fiber can cause excessive signal loss, even at a short reach when mating with newer MMF types (core diameter 50µm). Both OM1 and OM2 can only support very limited reach for links above 1G, and can no longer support system speed upgrades. In today’s data center, OM1 and OM2 MMF types aren’t recommended for new greenfield installation.

OM1 and OM2 have higher fiber cable attenuation (3.5 dB/km) compared to OM3 and OM4 (3.0dB/km); therefore, the appropriate link budget may not be met.

Currently, OM3 and OM4 are the most popular MMF types deployed in modern data centers. OM3 MMF can support the latest Ethernet and Fibre Channel applications with reduced reach; however, cautions must be taken when mating legacy OM3 MMF with new bend-insensitive MMF (BI-MMF). The slight difference in fiber geometry could cause additional loss, negatively impacting cable performance.

OM4 BI-MMF is recommended for new fiber installation or fiber upgrade and replacement projects because the latest application standards are developed based on OM4 specifications.


In a nutshell, Multi-mode fiber is typically cost effective for inside buildings or corporate campuses where the lengths don’t exceed a few hundred meters. When it comes to network speed upgrades, our recommendation is that you replace old OM1/OM2 or legacy OM3 with high-quality OM4 BI-MMF cabling to prevent light from escaping and causing bend-induced attenuation. This leads to better performance, higher bandwidth capabilities and improved optical performance. FS.COM will always offer a best cabling solution for you. For more details, please contact