Ethernet standards from 10 Mbit/s to 400 Gbit/s
Ethernet is defined by the IEEE 802.3 family, and each physical-layer (PHY) standard pairs a speed with a specific medium and reach. This reference lists the common copper and fibre standards — from legacy 10BASE-T to modern 400GbE — with the IEEE designation, maximum speed, required cable, and maximum distance.
How it works
Each Ethernet standard name encodes three things. The leading number is the speed (10, 100, 1000 Mbit/s, or in Gbit/s for 10G and up). BASE means baseband signalling — the whole cable carries one Ethernet signal. The suffix names the medium: -T is twisted-pair copper, -SX/-SR is short-reach multimode fibre, -LX/-LR is long-reach single-mode fibre, and a trailing digit (SR4, LR4) gives the number of parallel lanes or wavelengths.
Copper BASE-T standards almost universally specify a 100 m channel; going faster on copper requires a higher cable category to manage crosstalk and attenuation — Cat5e for gigabit, Cat6 for 5G, Cat6a for 10G. Fibre variants trade copper’s distance limit for reach: multimode SR optics reach hundreds of metres cheaply, while single-mode LR optics reach 10 km or more.
Tips and notes
- Auto-negotiation lets two ports agree on the fastest common speed and duplex; mismatched manual settings are a classic cause of slow or unstable links.
- 2.5GBASE-T and 5GBASE-T (NBASE-T) are the practical upgrade path on existing office wiring and are widely used for Wi-Fi 6/6E access-point uplinks.
- Fibre transceivers are modular (SFP, SFP+, QSFP); the same switch port can run different reaches just by swapping the optic.
- Distances are the standardised maximums for a clean channel; connectors, patch panels, and cable quality reduce real-world reach.