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Multimode Fiber Types:OM1 OM2 OM3 OM4 OM5

May 19, 2026

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There are five standardized multimode fiber types: OM1, OM2, OM3, OM4, and OM5 - each defined by ISO/IEC 11801 and differentiated by core diameter, bandwidth, maximum transmission distance, and supported data rate. All five carry multiple light modes simultaneously through a 50 µm core (62.5 µm for OM1 only), making them ideal for high-speed, short-to-medium-distance links inside data centers, enterprise buildings, and campus networks - typically up to 550 m. Here is how they differ at a glance: OM1 (62.5 µm core, 200 MHz·km, up to 10 Gbps/33 m) is legacy and largely obsolete; OM2 (50 µm, 500 MHz·km, 10 Gbps/82 m) suits low-speed SMB links; OM3 (50 µm, 2,000 MHz·km, 100 Gbps/100 m) is today's data-center standard; OM4 (50 µm, 4,700 MHz·km, 100 Gbps/150 m) serves high-performance and core-layer deployments; and OM5 (50 µm, 28,000 MHz·km, SWDM-capable, 400 Gbps support) is built for ultra-high-density hyperscale environments. This guide covers every multimode fiber type in detail: core specs, jacket color, light source, real-world use cases, and a step-by-step selection guide so you choose the right OM grade for your exact speed, distance, and budget requirements.

 

Multimode fiber is a type of optical fiber that carries multiple light signals simultaneously through a larger core - typically 50 or 62.5 microns in diameter.multimode fiber uses many light modes at once, which is why it suits the dense, high-bandwidth environments found in server rooms, enterprise networks, and IDC facilities.

 
 

1. Overview of Multimode Fiber Types

 

​"OM" stands for Optical Multimode.​ The number suffix (1 through 5) indicates the performance grade, defined by the IEC 60793-2-10 fiber standard and the ISO/IEC 11801 cabling standard. Each successive grade raises the minimum overfilled launch (OFL) bandwidth and effective modal bandwidth (EMB), enabling higher data rates over longer distances. Starting with OM2, all grades standardized on a 50 µm core diameter (vs. OM1's 62.5 µm) to reduce modal dispersion - the primary factor limiting bandwidth in multimode fiber.
The table below compares all five multimode fiber types across the six specifications that matter most for network design:
(The existing spec comparison table in Section 7 should be moved here or duplicated here as the primary reference table - see Section 7 optimization note below.)

why do we need OM grades? The core reason is that network speeds keep marching upward. The early multimode fibers couldn't keep up with new bandwidth demands, so manufacturers continuously pushed the technology and rolled out higher‑grade models.

 

the differences from OM1 to OM5 across the key dimensions of bandwidth speed transmission distance light source and application scenarios

2. Multimode Fiber Types Development History: OM1

 

OM1 - Legacy Grade (Largely Obsolete)​
Spec
OM1 Value
Core Diameter
62.5 µm
Jacket Color
Orange
Light Source
LED (850/1300 nm)
Bandwidth (OFL)
200 MHz·km @ 850 nm
Max Distance @ 1 Gbps
300 m
Max Distance @ 10 Gbps
33 m
IEEE Standard
802.3 (1000BASE-SX)
When OM1 is still found:​ OM1 remains in legacy CCTV, building access control, and pre-2000 campus backbone installations. It is not recommended for any new deployment. If you are upgrading an existing OM1 link, replacing it with OM3 at equivalent cost eliminates distance and bandwidth constraints in one step.

OM1: the "big brother" of the multimode fiber family. OM1 is gradually heading into retirement; you'll hardly see OM1 fiber on the market nowadays. I'd suggest newcomers not even bring it up with fiber vendors-otherwise you risk looking technically inexperienced.
 
OM1 is the earliest multimode fiber model, with a 62.5‑micron core, an orange outer jacket, an LED light source, and a bandwidth of only 200 MHz·km. Its performance is pretty weak: at 1Gbps it can reach 300 meters max, and at 10Gbps it manages just 33 meters-enough only for early 100MbE needs.

OM1 is the earliest multimode fiber model, an orange outer jacket with an LED light source, and a bandwidth of only 200 MHz·km

Today OM1 is basically obsolete. New network builds almost never use it; only a handful of legacy systems still hang on. Just like how barely anyone uses a 2G phone anymore, OM1 has become a relic of the past.
 
Let me tell you about a real‑world OM1 encounter. I once went to an old factory site for a network upgrade. Their CCTV surveillance system was still running on OM1 fiber, with a transmission distance of just over 200 meters, and the video would stutter now and then. Buying new OM1 wouldn't have been cheap, either. After talking it over with the client, I ended up replacing everything with OM3 fiber. The cost came out about the same, but all those annoying little problems disappeared instantly.

OM1 Multimode fiber has a 62.5‑micron core,

3. Multimode Fiber Types Development History: OM2

 
OM2 - Transitional Grade (Declining Market Share)​
Spec
OM2 Value
Core Diameter
50 µm
Jacket Color
Orange
Light Source
LED (850/1300 nm)
Bandwidth (OFL)
500 MHz·km @ 850 nm
Max Distance @ 1 Gbps
600 m
Max Distance @ 10 Gbps
82 m
IEEE Standard
802.3 (1000BASE-SX, 10GBASE-SR)
Best for:​ Low-speed (1 Gbps), short-haul SMB links where cost is the primary constraint. OM2 is being phased out in favor of OM3, which costs only marginally more and delivers significantly better performance headroom. Not recommended for new installations targeting 10 Gbps or above.
OM2 is an upgrade from OM1, with the core diameter shrunk to 50 microns. We've already explained in a previous article that the reason is modal dispersion-a 50‑micron core simply performs better. The outer jacket is still orange, the light source is still LED, but the bandwidth jumps to 500 MHz·km.
 
Consider this: given current technology trends, OM2 is already a transitional model in the multimode fiber family. Put bluntly, it's on its way out as well.
 
Right now, OM2 mostly appears in the internal networks of small to medium businesses or in short‑distance cabling jobs that don't need high speeds. But as businesses demand more bandwidth, OM2 is steadily being replaced by the higher‑grade OM3 and OM4, and its market share keeps shrinking.

OM2's performance pulls well ahead of OM1's: at 1Gbps it can go 600 meters-twice OM1's reach-and at 10Gbps it hits 82 meters

 

4.  Development History of Multimode Fiber Types: OM3

 
OM3 - Current Data Center Standard
Spec
OM3 Value
Core Diameter
50 µm
Jacket Color
Aqua (light green)
Light Source
VCSEL (850 nm)
Bandwidth (OFL/EMB)
2,000 / 2,000 MHz·km
Max Distance @ 10 Gbps
300 m
Max Distance @ 40 Gbps
100 m
Max Distance @ 100 Gbps
100 m
IEEE Standard
802.3ae/ba (10GBASE-SR, 40GBASE-SR4, 100GBASE-SR10)
OM3 introduced VCSEL (Vertical Cavity Surface Emitting Laser)​ as the standard light source, replacing LED. VCSEL dramatically reduces modal dispersion and enables the bandwidth jump from 500 MHz·km (OM2) to 2,000 MHz·km. This makes OM3 the default choice for enterprise data centers, financial institution cabling, and IDC backbone links at 10–100 Gbps. The upgrade path is non-disruptive: moving from 10 Gbps to 40 Gbps requires only transceiver replacement - no recabling.

 

OM3 marks a major milestone in multimode fiber development-it came along just when modern data centers were crying out for high-speed transmission. You might say it's the default choice for today's IDC data centers.
 
OM3 keeps the 50-micron core, switches to a light-green outer sheath, and uses a more efficient light source: the Vertical Cavity Surface Emitting Laser (VCSEL). Its bandwidth skyrockets to 2000 MHz·km.
 
Performance-wise, OM3 is impressive: it handles 10 Gbps over 300 meters, and within 100 meters it supports blazing-fast 40 Gbps and 100 Gbps. That's why OM3 has become the "standard" for modern data centers-internet companies and financial institutions routinely pick OM3 for in-house data center cabling.

OM3 keeps the 50-micron core, switches to a light-green outer sheath, and uses a more efficient light source: the Vertical Cavity Surface Emitting Laser (VCSEL).

It's also highly compatible. If you later want to upgrade to 40 Gbps, just swap out the optical modules; there's no need to rerun cables, saving you a ton of hassle.
 

5.  Development History of Multimode Fiber Types – OM4

 

OM4 - High-Performance Grade (Recommended for HPC and Core Layers)​

Spec OM4 Value
Core Diameter 50 µm
Jacket Color Aqua (light green, same as OM3)
Light Source VCSEL (850 nm)
Bandwidth (OFL/EMB) 4,700 / 4,700 MHz·km
Max Distance @ 10 Gbps 550 m
Max Distance @ 40 Gbps 150 m
Max Distance @ 100 Gbps 150 m
Backward Compatible With OM3 (fully interoperable)
IEEE Standard 802.3ba (40GBASE-SR4, 100GBASE-SR10)

OM4's key advantage over OM3 is 250 m of additional reach at 10 Gbps (550 m vs. 300 m) and 50 m of additional reach at 40/100 Gbps (150 m vs. 100 m). Because OM4 is fully backward compatible with OM3 infrastructure, it can be mixed in existing OM3 deployments without signal degradation. Best for:​ High-performance computing (HPC) clusters, cloud data center core layers, and enterprise core networks where both bandwidth and low-latency are critical.


OM4 is an upgraded version of OM3. The core stays at 50 microns, the outer sheath remains light green like OM3, and it's fully backward compatible (meaning you can mix OM4 and OM3 fibers). The light source is still VCSEL, but bandwidth jumps to 4700 MHz·km-nearly double that of OM3. That makes OM4 the high-performance pick among multimode fibers.
 
On the performance front, OM4 raises the bar: it reaches 550 meters at 10 Gbps, a 250-meter boost over OM3, and supports 40 Gbps and 100 Gbps up to 150 meters. OM4 is purpose-built for demanding environments like high-performance computing, data center core layers, and enterprise core networks, where both bandwidth and low latency are critical.

On the performance front, OM4 raises the bar: it reaches 550 meters at 10 Gbps, a 250-meter boost over OM3, and supports 40 Gbps and 100 Gbps up to 150 meters.

For businesses that want extra upgrade headroom, OM4 is also a smart pick.
 

OM3 vs. OM4 - Quick Decision Rule:​

  • If your links are ≤ 100 m at 40/100 Gbps → OM3 is sufficient and more cost-effective
  • If your links are 100–150 m at 40/100 Gbps, or 300–550 m at 10 Gbps → choose OM4
  • If you anticipate upgrading to 400 Gbps in a high-density environment → go directly to OM5
 

6.  Development History of Multimode Fiber Types – OM5

OM5 - Wideband Multimode Fiber (WBMMF) - Future-Proof Grade
Spec
OM5 Value
Core Diameter
50 µm
Jacket Color
Lime green (distinct from OM3/OM4 aqua)
Light Source
VCSEL (850–953 nm, multi-wavelength)
Bandwidth (OFL/EMB)
28,000 / 3,500 MHz·km
SWDM Channels
4 wavelengths × ≥28 Gbps each
Max Distance @ 40 Gbps (SWDM4)
440 m
Max Distance @ 100 Gbps (SWDM4)
150 m
Forward Compatible With
OM4
IEEE Standard
802.3cm (100GBASE-SR4, 400GBASE-SR8)
OM5's differentiating feature is SWDM (Short Wavelength Division Multiplexing)​: it supports at least four wavelength channels across the 850–953 nm window, each carrying ≥28 Gbps of data. This allows a single OM5 fiber strand to carry the aggregate bandwidth that would otherwise require multiple OM4 fibers - reducing fiber count and cable tray congestion in ultra-high-density data centers by up to 75%. OM5 is backward compatible with OM4 infrastructure. Cost premium:​ OM5 fiber costs approximately 60–70% more per meter than OM4. It is cost-justified only in hyperscale data centers targeting 400 Gbps+ with severe space or weight constraints on cable pathways.

OM5 is the newest multimode fiber, often called Wideband Multimode Fiber (WBMMF). It keeps the 50-micron core and light-green sheath, is forward-compatible with OM4,

The killer feature of OM5 is Short Wavelength Division Multiplexing (SWDM). It supports at least four wavelength channels in the 850–953 nm range, each delivering a minimum of 28 Gbps. That means a single OM5 fiber can carry multiple signals at once, drastically increasing data throughput without adding more fibers-perfect for high-density data centers.

The killer feature of OM5 is Short Wavelength Division Multiplexing (SWDM). It supports at least four wavelength channels in the 850–953 nm range, each delivering a minimum of 28 Gbps

Imagine an enormous data center from a major internet company with sky-high cabinet density and a need for 100 Gbps or even 400 Gbps in tight spaces. Pair OM5 fiber with SWDM, and you hit those high-density, high-speed requirements without ballooning your cabling costs. This is where multimode fiber is headed. 
 

7.  How to Choose the Right Multimode Fiber Type: OM1 vs OM2 vs OM3 vs OM4 vs OM5


Now that we've covered the differences, the big question is: how do you choose? It's actually straightforward-just follow these three steps.
Step 1: Pin Down Your Speed Requirement
For 1 Gbps or less and distances up to 600 meters: OM2 is the value champ.
For 10 Gbps and distances up to 300 meters: go with OM3. If you need 300–550 meters, step up to OM4.
For 40 Gbps, 100 Gbps, or higher: OM3 works out to 100 meters, OM4 to 150 meters. For high-density environments, go straight to OM5.

Core Diameter Wavelength Bandwidth Transmission Rate Difference Between OM1 OM2 OM3 OM4 and OM5

Step 2: Think About Future Upgrades
If you're building a new network, leave room to grow. Don't lock yourself into an outdated standard. For instance, if you need 10 Gbps today but plan to move to 40 Gbps later, go with OM4 from the get-go. The upfront cost is a little higher, but you'll avoid a disruptive rewiring job down the road-saving you money and headaches. For high-density data centers, choose OM5 for a future-proof, one-and-done solution.
Step 3: Factor in Your Budget
Costs vary widely: OM5 > OM4 > OM3 > OM2 > OM1. If your budget is tight and your needs are clear, pick the lowest tier that still meets your requirements. If you have some financial wiggle room and foresee upgrades, it's worth investing in a higher tier to avoid expensive rework. Adjust your choice to fit your budget.
 
Specification OM1 OM2 OM3 OM4 OM5
Core Diameter (µm) $62.5 $50 $50 $50 $50
Wavelength (nm) $850 850 $850 $850 $850 - 953
Bandwidth (MHz·km) $160 $500 $2000 $4700 $3500
Transmission Rate (Gbit/s) $1 - 10 $1 - 10 $10 - 100 $10 - 100 $40 - 100
WDM Support No No No No Yes

8.  Summing Up Multimode Fiber


Let's recap the key takeaways. The OM grades of multimode fiber are essentially the story of bandwidth and speed upgrades-from OM1 to OM5, performance keeps climbing, and the ideal use case has expanded from ordinary enterprise networks all the way to hyperscale data centers. You don't need to blindly chase the highest grade, and you shouldn't cheap out on too low a grade either. Just base your decision on "speed need + transmission distance + future upgrade plans," and you'll land on the perfect fiber model.

 

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