The maximum distance for 1 Gbps Ethernet over multimode fiber ranges from 275 meters on OM1 to 550 meters on OM2, OM3, and OM4 fibers depending on fiber type and quality.

Maximum Distances by Fiber Type

• OM1 (62.5 µm core, LED source, 200 MHz·km bandwidth): Supports up to 275 meters at 1 Gbps, typically used for short-distance LANs and low-speed applications .
• OM2 (50 µm core, LED source, 500 MHz·km bandwidth): Can reach up to 550 meters at 1 Gbps, suitable for medium-distance LANs .
• OM3 (50 µm core, laser-optimized, 2,000 MHz·km bandwidth): Supports up to 550 meters at 1 Gbps, designed for higher-speed networks and longer distances than OM1/OM2 .
• OM4 (50 µm core, laser-optimized, 4,700 MHz·km bandwidth): Also supports up to 550 meters at 1 Gbps, offering improved performance and future-proofing for high-speed applications .
• OM5 (Wideband multimode fiber, SWDM capable): While optimized for higher data rates and wavelength division multiplexing, it can also support 1 Gbps over similar distances as OM4, though its main advantage is at higher speeds .

Factors Affecting Maximum Distance

1. Bandwidth and Modal Dispersion: Higher bandwidth fibers (OM3/OM4) reduce modal dispersion, allowing longer distances at the same data rate .
2. Light Source: LEDs are used in OM1/OM2, while VCSEL lasers are used in OM3/OM4, providing more precise light injection and longer reach .
3. Connectors and Splices: Poor-quality connectors or excessive splices can introduce signal loss, reducing effective distance .
4. Cable Management: Excessive bends, twists, or stress on the fiber can degrade performance and shorten maximum transmission distance .

Practical Considerations

For 1 Gbps Ethernet, OM2, OM3, and OM4 fibers are generally preferred for distances beyond 300 meters, while OM1 is suitable only for short links. Choosing laser-optimized fibers (OM3/OM4) ensures better performance, lower attenuation, and future scalability for higher-speed upgrades. Proper installation, high-quality connectors, and minimal splicing are essential to achieve the maximum rated distances.