Cat5 Ethernet Cable: Specs, Features, Pros & Cons
Category 5 is a withdrawn standard that can still carry gigabit Ethernet. Published in the mid-nineties with a hundred megahertz of tested bandwidth, it carried fast Ethernet into essentially every office in the world, and when the gigabit standard arrived it was specified to run over this grade too, across a full hundred-meter channel using all four pairs, where fast Ethernet had used only two.
Real gigabit deployments then exposed parameters the original specification had not tested tightly enough, particularly return loss and the behavior of crosstalk at the far end of a run. The standards bodies answered with an enhanced version and withdrew this one from recognition for new installations.
Cable already in a wall is not suddenly broken by that decision, and a link running at full speed on it will keep running. But there is no reason to buy it, and in most places you cannot.
It supports the highest power-over-Ethernet tier despite its age, since power delivery depends more on conductor size than on tested bandwidth, and it has no shielding or alien crosstalk limits. Physically it is four unshielded pairs ending in the same RJ45 plug as every later grade, so nothing on the outside gives its age away except the print on the jacket.
Buildings wired in the late 1990s very likely have it behind the wall plates, and it explains why a link there negotiates a gigabit but never multi-gig.
Category strengths
Where the Cat5 Ethernet Cable trails the median
- A much lower maximum data rate ?1 Gbps vs 10 Gbps (median)
- A much lower 10 Gigabit reach ?0 m vs 42.5 m (median)
- No 10 Gigabit Ethernet ?
- No recognition for new installs ?
- A much lower bandwidth ?100 MHz vs 375 MHz (median)
- No multi-gig (2.5G / 5G) ?
How this VS Score was computed
Score 23: each known spec is measured against the median of all ethernet cables (8 products), then weighted; 50 means level with that median. In classes of six or more, a value beyond the class’s 10th–90th percentile range counts as that limit, so one extreme product cannot set the scale. 79% of the scoreable weight could be used; unknown values, features not applicable to this class and proxies (battery capacity where a rated life exists) add or remove nothing.
| Specification | This product | Cohort median | Score weight | Points moved |
|---|---|---|---|---|
| Maximum data rate | 1 | 10 | 3 | −135.0 |
| Native RJ45 connector | Yes | 75% of the class have it | 2 | +100.0 |
| 10 Gigabit reach | 0 | 42.5 | 2 | −96.0 |
| 10 Gigabit Ethernet | No | 63% of the class have it | 2 | −96.0 |
| Recognition for new installs | No | 75% of the class have it | 2 | −96.0 |
| Bandwidth | 100 | 375 | 2.5 | −92.5 |
| Multi-gig (2.5G / 5G) | No | 75% of the class have it | 1.5 | −72.0 |
| Shielded construction | No | 38% of the class have it | 1 | −48.0 |
| Alien crosstalk limits | No | 33% of the class have it | 1 | −48.0 |
| Reach at top speed | 100 | 100 | 1.5 | +0.0 |
| Typical shielding | U/UTP (unshielded) | U/UTP (unshielded) | 1.5 | +0.0 |
| Maximum PoE power | 90 | 90 | 1.5 | +0.0 |
Not scored: Gigabit Ethernet (standard for the class (88% have it)); 25G / 40G Ethernet (not applicable: only 13% of this class have it); Conductor material (unknown: not scored); Snagless boots (unknown: not scored); PoE++ (Type 4, 90 W) (standard for the class (88% have it)); Backward compatibility (standard for the class (100% have it)).
Editor’s note
Category 5 is the cable that made Ethernet ordinary. Published in ANSI/TIA/EIA-568-A in 1995 with 100 MHz of tested bandwidth, it carried 100BASE-TX into every office in the world and, once IEEE published 802.3ab, gigabit as well: 1000BASE-T is specified to run over Category 5 across a full 100-meter channel using all four pairs.
The complication is what happened next. Real-world gigabit exposed parameters the original specification did not test tightly enough, particularly return loss and far-end crosstalk. Rather than rewrite Cat 5, TIA published Category 5e in 2001 with tighter limits and withdrew plain Cat 5 from the standard. Most cable sold as Cat 5 in the late nineties met the 5e limits, which is why so much legacy Cat 5 does run gigabit without complaint. That is a happy accident of manufacturing tolerance, not a guarantee, and an installer certifying a link will test it to 5e or refuse to sign it off.
ISO's numbering adds a second wrinkle. Class D originally described Cat 5, and from the 2002 edition it describes Cat 5e. So a Class D certificate on a modern report means 5e, whatever the cable jacket says.
The practical rules are simple. Existing Cat 5 that tests clean at gigabit can stay. It will not do 2.5 Gigabit reliably, because 2.5GBASE-T was written against Cat 5e, and it will never do 10 Gigabit. Power over Ethernet is fine, including the 90-watt classes, since the PoE standards name Category 5 as the floor for high power.
Nobody should buy Cat 5 today, and nobody sells it. Its value now is diagnostic: knowing what is in the wall tells you whether a multi-gig switch upgrade will deliver.
Specifications
Quality bars show where each figure sits between the lowest and highest of the 8 ethernet cables this VS Score is measured against.
Speed & reach
Construction & shielding
Power & connectors
Standards & status
Sources and verification
Where the specifications come from
- Official product pagecsagroup.org
- Datasheet or manualstandards.ieee.org
Verification
- First published
- Specifications last checked
- Sheet completeness
- 22 of 28 specifications verified; the rest show as Unknown and are never estimated or scored
- Page type
- Product specification page — Compiled from the manufacturer’s published specifications and the cited sources; this is not a hands-on test.
- Basis
- Research-based: specifications and editorial text were compiled from the documents listed here and the manufacturer’s published data. We have not tested this unit ourselves; where independent measurements are mentioned they belong to the linked publication.
Ratings & reviews
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The bottom line
The Cat5 Ethernet Cable earns a VS Score of 23, below the median of the 8 ethernet cables it is measured against (a score of 50 is level with that median).
- Who it’s for
- Existing building wiring that already tests clean at gigabit and only needs to keep doing that.
- Who should look elsewhere
- New installations and any multi-gig plan. 2.5GBASE-T was written against Cat 5e, not Cat 5.
- The trade-off that matters
- It usually runs gigabit fine because most Cat 5 was manufactured to 5e tolerances, but nothing about that is guaranteed or certifiable.
- The main alternative
- Cat5e Ethernet Cable: the tighter grade that replaced it and adds multi-gig
The VS Score is calculated from the weighted specifications above, each measured against the median of comparable ethernet cables — a shortlisting guide, not a substitute for your own priorities. See how we score.