OM4 vs OM5: Wideband Fibre in Practice
Quick answer / TL;DR: Short answer: OM4 and OM5 have the same 4700 MHz-km bandwidth at 850 nm, so a single-channel link reaches the same distance on either. OM5 adds effective bandwidth at 953 nm, which enables shortwave division multiplexing to combine several wavelengths on one fibre and reduce fibre count. Choose OM5 only when the design uses SWDM or when fibre count is the constraint; otherwise OM4 gives the same result for less money. OM5 is conventionally lime green.
Fiber cords: two connector families, two fiber types, three polish options.OM5 is often described as the next step after OM4, which suggests a speed increase. It is not faster. OM5 adds usable bandwidth at a second wavelength so that shortwave division multiplexing can put several channels on one fibre.
If the plan is a single channel at 850 nm, OM4 and OM5 behave almost identically. The value appears only when the transmission scheme uses the extra band.
What the Two Fibres Actually Specify
The headline bandwidth figure is identical, which is the source of most confusion. The difference is a second specification point at a longer wavelength in the shortwave window.
| Property | OM4 | OM5 |
|---|
| Bandwidth at 850 nm | 4700 MHz-km | 4700 MHz-km |
| Bandwidth at 953 nm | not specified | about 2470 MHz-km |
| SWDM support | no | yes, four wavelengths |
| 10G distance at 850 nm | 400 m | 400 m |
| Jacket colour | aqua or violet | lime green |
| Relative cost | baseline | higher |
SWDM uses four wavelengths between 850 and 953 nm, each carrying a channel. That turns one duplex pair into four lanes, which is how OM5 reduces fibre count in a backbone without moving to parallel optics.
When the Extra Band Matters
Three conditions justify OM5, and outside them the specification buys nothing.
- The transceivers are SWDM parts, which are a specific product category rather than a general capability
- Fibre count or duct capacity is the binding constraint, so putting more channels on existing fibre saves construction
- The installation is new and the design life is long enough that SWDM optics will plausibly be used later
- If none apply, OM4 with parallel optics or single-mode is usually simpler
- If the run exceeds 400 m at 10G, single-mode is the answer regardless
The Economics Compared With Single-Mode
OM5 sits between OM4 and single-mode in cost and capability. Its advantage is that it uses inexpensive shortwave optics, which is the reason multimode persists in data centres at all.
Where runs are long or the speed path is unclear, single-mode with low-cost optics has closed much of the historical price gap. The decision is therefore about the optics ecosystem a site already standardises on, not only about the cable.
Real-World Applications
Data centre spine with limited tray capacity
This is the textbook OM5 case. Existing duplex fibre runs to each row, tray capacity is full, and SWDM transceivers allow four channels per pair. Verify that the transceivers are genuinely SWDM parts and that the link loss budget accounts for the extra connectors.
New build with no transceiver decision yet
Specifying OM5 without a SWDM plan adds cost for capability that may never be used. OM4 is the safer default, with single-mode considered for any run that might exceed 400 m.
Mixed fleet with legacy OM3
An OM3 backbone upgraded with OM5 patch cords performs to OM3 in the sections that remain OM3. The category of the weakest section governs, so upgrade the whole channel or accept the lower limit.
Standards and Verification
OM5 is a published fibre category with defined bandwidth at two wavelengths, which is what makes the SWDM claim checkable.
- TIA-492AAAE: the OM5 wideband multimode fibre specification
- ISO/IEC 11801-1: OM5 channel class and distance support
- IEEE 802.3: the Ethernet physical layers used with multimode fibre
- IEC 60793-2-10: multimode fibre product specifications
- SWDM Alliance specifications: the wavelength grid and lane structure used by SWDM transceivers
Verification is a loss budget at the wavelength actually in use, plus confirmation that the transceiver is the SWDM type. A field test at 850 nm alone will not demonstrate the 953 nm capability, so acceptance records should state which wavelengths were measured and with which source.
Related reading: Fiber cable guide: single-mode, multimode and construction — blogs/news/fiber-cable
Related reading: OM4 fiber cable: 4700 MHz-km and 400 m — blogs/news/om4-fiber-cable
Related reading: OM5 fiber cable: wideband multimode — blogs/news/om5-fiber-cable
Frequently Asked Questions
Is OM5 faster than OM4?
No. Both specify 4700 MHz-km at 850 nm, so single-channel distance is the same. OM5 adds bandwidth at 953 nm to support shortwave division multiplexing.
Do I need OM5 for 40G or 100G?
No. OM4 supports 40G and 100G to about 150 m using parallel optics. OM5 becomes relevant when SWDM is used to reduce fibre count.
Can I use OM4 and OM5 together?
Yes, and the link performs to OM4 limits unless every section is OM5 and the transceivers use the 953 nm band. Document the mix.
How do I identify OM5?
The jacket is conventionally lime green and the print states OM5. Colour alone is not definitive, so read the print.
When should I choose single-mode instead?
When runs exceed about 400 m at 10G, or when the speed path is uncertain over a long service life. Single-mode removes distance as a design constraint.
Sourcing cables for a project, a store, or a private-label line? Contact our B2B sales team for specifications, certification evidence, and volume terms – FOB and CIF options available. Request a quote or sample.
