What Is the Difference Between OM1, OM2, OM3, OM4 and Singlemode Fiber?

When building a modern network or server infrastructure, many customers ask the same question: which fiber optic cable should they choose — OM1, OM2, OM3, OM4 or Singlemode?

This question often comes up when:

• connecting SFP and SFP+ modules;
• installing a local network;
• building a server room;
• setting up 10G or 40G Ethernet;
• connecting switches and data centers.

At first glance, all fiber optic types may look similar, but there are major differences between them:

• maximum speed;
• transmission distance;
• laser type;
• transceiver compatibility;
• equipment cost;
• future upgrade potential.

In short: OM1, OM2, OM3 and OM4 are multimode fiber types, while Singlemode is designed for long distances and backbone network lines.

In this article, we explain the difference between these fiber optic types in simple terms and help you choose the best solution for your network.

What Are Multimode and Singlemode Fiber?

OM1, OM2, OM3 and OM4 are multimode fiber types.

Singlemode is a single-mode fiber type.

The main differences are:

• core diameter;
• signal transmission distance;
• high-speed support;
• laser type;
• cost of active equipment.

Comparison Table: OM1, OM2, OM3, OM4 and Singlemode

OM1 Fiber Optic Cable

Main Characteristics of OM1

• Type: Multimode
• Core: 62.5/125 µm
• Color: orange
• Supports 1G and 10G Ethernet
• Up to 33 meters at 10G

OM1 is one of the oldest multimode fiber standards. Today, it is mostly found in older networks or used when modernizing legacy infrastructure.

Due to its speed and distance limitations, OM1 is rarely used in new modern projects.

Advantages of OM1

• low cost;
• can be used with older infrastructure;
• suitable for basic 1G networks.

Disadvantages of OM1

• very short 10G distance;
• outdated standard;
• limited scalability;
• not suitable for modern data centers.

If you are building a new network, OM1 is usually not recommended today. In most cases, OM3 or Singlemode is a better choice.

OM2 Fiber Optic Cable

Main Characteristics of OM2

• Type: Multimode
• Core: 50/125 µm
• Color: orange
• Supports 1G and 10G Ethernet
• Up to 82 meters at 10G

OM2 is a more modern multimode fiber option compared to OM1. It is often used for upgrading existing networks or for short-distance connections.

Advantages of OM2

• lower price;
• more affordable patch cords;
• suitable for basic tasks.

Disadvantages of OM2

• distance limitations;
• not the best option for modern data centers;
• less future upgrade potential.

OM3 Fiber Optic Cable

Main Characteristics of OM3

• Type: Multimode
• Core: 50/125 µm
• Color: aqua
• Supports 10G, 40G and 100G
• Up to 300 meters at 10G

OM3 is one of the most popular fiber optic types for modern server rooms and office networks.

It is commonly used:

• in server rooms;
• in data centers;
• with SFP+ modules;
• in 10 Gigabit Ethernet networks.

Advantages of OM3

• good balance between price and performance;
• supports high speeds;
• popular standard for modern equipment.

Disadvantages of OM3

• more expensive than OM2;
• shorter distance compared to Singlemode.

For most 10G server rooms, we most often recommend OM3 — it offers the best balance of price, speed and future upgrade potential.

OM4 Fiber Optic Cable

Main Characteristics of OM4

• Type: Multimode
• Core: 50/125 µm
• Color: aqua or violet
• Supports 10G / 40G / 100G
• Up to 550 meters at 10G

OM4 is an improved version of OM3 with longer transmission distance and higher bandwidth.

Advantages of OM4

• longer distance;
• stable operation at high speeds;
• strong future upgrade potential.

Disadvantages of OM4

• higher price;
• not always necessary for small offices.

What Is Singlemode Fiber?

Main Characteristics of Singlemode

• Type: Singlemode
• Core: 9/125 µm
• Color: yellow
• Very long transmission distance
• Supports modern high-speed links

Singlemode is used where long-distance transmission is required:

• backbone network lines;
• connections between buildings;
• provider networks;
• large data centers;
• high-speed communication channels.

Advantages of Singlemode

• signal transmission over kilometers;
• minimal signal loss;
• supports 100G speeds and higher;
• excellent future upgrade potential.

Disadvantages of Singlemode

• more expensive SFP/SFP+ modules;
• higher cost of active equipment;
• often not cost-effective for short distances.

If you need to build a connection between buildings or plan to scale your network for years ahead, Singlemode is usually the best solution.

Which Is Better: OM3 or OM4?

For most offices and 10G server rooms, OM3 is the optimal choice.

OM4 makes sense if:

• longer distances are required;
• network expansion is planned;
• high network loads are expected;
• a modern data center is being used.

When Should You Choose Singlemode?

• distance is more than 300–500 meters;
• backbone links are required;
• network scaling is planned;
• provider-grade equipment is used;
• high-speed communication links are required.

What to Consider When Choosing Fiber Optic Cable

• network speed;
• line length;
• type of SFP modules;
• switch compatibility;
• future upgrade potential.

It is also important to choose the right optical patch cords, SFP/SFP+ modules, fiber optic boxes, pigtails, LC/SC adapters and cross-connect equipment.

FAQ

Can OM3 be connected to OM4?

Yes, OM3 and OM4 are compatible with each other. However, the network will operate according to the characteristics of the weaker standard.

What color is Singlemode fiber?

Singlemode fiber is usually yellow.

Which is better for a server room — OM3 or Singlemode?

For most 10G server rooms, OM3 is optimal. Singlemode is better for long distances and backbone lines.

Does OM1 support 10G speed?

Yes, but only over very short distances — approximately up to 33 meters.

Does OM2 support 10G speed?

Yes, but only over short distances — approximately up to 82 meters.

Which fiber type is better for future upgrades?

If you need strong future upgrade potential, OM4 or Singlemode is usually the best choice.

Conclusion

OM1, OM2, OM3, OM4 and Singlemode have different purposes, and the right choice depends on your network requirements.

• OM1 — a very old standard for basic networks;
• OM2 — a budget option for short distances;
• OM3 — the optimal choice for most modern networks;
• OM4 — for high speeds and heavy network loads;
• Singlemode — for long distances and backbone lines.

At Net-Server, we regularly help customers choose fiber optic cable, SFP modules, optical patch cords, fiber optic boxes and cross-connect equipment for server rooms, offices and data centers.

If you are not sure which fiber optic cable is right for your network, contact us — we will help you choose the best solution for your equipment and budget.