Fiber Optic Cable Types: OS2 vs OM3 vs OM4 Buying Guide for IT Professionals (2026)

Fiber optic cable comes in multiple grades, each designed for a specific distance, speed, and application. Choosing the wrong fiber wastes money on overspec or, worse, fails to meet bandwidth requirements. This guide covers the five most common types: OS2, OM1, OM2, OM3, and OM4.

Fiber types at a glance

Single-mode vs multimode: the core decision

Single-mode (OS2) uses a 9-micron core that allows only one mode (path) of light to propagate. This eliminates modal dispersion, enabling distances of 10+ kilometers at 10 Gbps. Single-mode requires laser-based transceivers (SFP+) which cost more than the LED-based transceivers used with multimode.

Multimode (OM3/OM4) uses a 50-micron core that allows multiple light modes to propagate simultaneously. This limits distance but uses cheaper VCSEL (LED-like) transceivers. For data center runs under 300-400 meters, multimode is more cost-effective because the transceiver savings outweigh the cable cost difference.

Which fiber should you install?

For new data center builds: OM4 multimode for intra-building runs under 400m, OS2 single-mode for building-to-building backbone and anything over 400m. This dual approach is standard in modern data center design.

For campus/enterprise LAN: OS2 single-mode for building-to-building, OM3 or OM4 for building risers and floor distribution. The transceivers are now cheap enough that single-mode is worth considering even for shorter runs if you want maximum future-proofing.

For new residential/small business: If you are pulling fiber at all, pull single-mode OS2. The cable cost difference is minimal and it provides unlimited bandwidth headroom.

Connector types

The most common fiber connectors in order of market share: LC (most common, small form factor, used in SFP/SFP+ modules), SC (larger, push-pull, common in telecom and older networks), ST (bayonet twist, legacy), MPO/MTP (multi-fiber, used for 40G/100G/400G trunk cables).

For new installations, specify LC connectors unless you have a specific reason to use something else. LC is the de facto standard for modern networking equipment.

Shop fiber optic products

• Fiber optic patch cables (OS2, OM3, OM4 in LC, SC, ST)
• Network patch cables
• Connectors and keystones
• Bulk cable

Planning a fiber deployment? Contact our team for fiber selection guidance and volume pricing on patch cables and trunk assemblies.

Find your competitor equivalent:

Cross-reference hub | Compression lugs | Split bolts | Insulated taps | Mechanical lugs