Cat 5
Ethernet Cables · 8 specs
Direct Answer
Category 5 (Cat 5) is a legacy twisted-pair copper cable standard defined in ANSI/TIA/EIA-568-A. Rated for frequencies up to 100 MHz, it was the foundational medium for 100BASE-TX Fast Ethernet (100 Mbps) over distances up to 100 meters, utilizing two of its four twisted pairs.
Source: ANSI/TIA/EIA-568-A (1995) / ISO/IEC 11801:1995 Class D · Last reviewed Aug 28, 2026
Specs
| Frequency Bandwidth | 100 MHz |
| Max Bandwidth / Data Rate | 100 Mbps |
| Max Channel Length | 100 m |
| Wire Pairs | 4 pairs |
| Active Pairs (100BASE-TX) | 2 pairs |
| Standard Connector | 8P8C (RJ45) |
| Typical Shielding | U/UTP (Unshielded) |
| Channel Classification | ISO/IEC 11801 Class D |
Historical Role and Obsolescence
Introduced in 1995 to replace Cat 3 and Cat 4, Cat 5 provided the electrical characteristics required for 100BASE-TX Fast Ethernet. While it physically contains 4 unshielded twisted pairs (UTP), 100BASE-TX only transmits across 2 pairs (pins 1, 2, 3, and 6), leaving the other 2 pairs unused or available for basic analog telephone signals.
Cat 5 was formally deprecated and superseded by Cat 5e in 2001. Although Cat 5 can occasionally support Gigabit Ethernet over short runs, it lacks the strict crosstalk and return loss specifications required to reliably sustain 1000BASE-T across the full 100-meter channel distance.
Differences from Cat 5e
Cat 5 and Cat 5e share the same 100 MHz maximum testing frequency, but Cat 5e enforces much tighter manufacturing tolerances and defines strict performance thresholds for Power Sum Near-End Crosstalk (PS-NEXT), Equal-Level Far-End Crosstalk (ELFEXT), and return loss.