Cable Category Speed & Distance Calculator
Determine the maximum supported speed and transmission distance for standard Ethernet cable categories (Cat5e through Cat8), and estimate signal attenuation over a given run length.
Formulas Used
Attenuation (dB):
A(f, L, T) = Aref × √(f / fref) × (L / 100) × [1 + 0.004 × (T − 20)]
- Aref = worst-case insertion loss at 100 MHz per 100 m (TIA-568-C.2)
- f = frequency of interest (MHz); fref = 100 MHz
- L = cable length (m); T = ambient temperature (°C)
- √(f) term models skin-effect dominated conductor loss
- Temperature coefficient: +0.4 %/°C above 20 °C (TIA-568-C.2 §6.3)
Propagation Delay (ns):
tprop = L / (VF × c) × 10⁹
- VF = velocity factor (fraction of speed of light in the dielectric)
- c = 2.998 × 10⁸ m/s
Maximum Distance is taken directly from IEEE 802.3 and TIA-568 channel length limits per speed standard.
Assumptions & References
- Attenuation values are worst-case channel limits from TIA-568-C.2 and ISO/IEC 11801:2017.
- Maximum distances follow IEEE 802.3 (10BASE-T through 40GBASE-T) permanent link / channel specifications.
- Cat8 is limited to 30 m for 10/25/40 Gbps per ANSI/TIA-568-C.2-1 and IEEE 802.3bq.
- Cat6 supports 10 Gbps up to 55 m (IEEE 802.3an); Cat6a extends this to 100 m.
- Velocity factors are typical values for solid-core UTP; shielded (STP/SFTP) cables may differ slightly.
- Practical throughput estimate assumes up to 15 % overhead from attenuation-related retransmissions; actual performance depends on switch/NIC quality and crosstalk.
- Calculations assume a single horizontal run; patch cords, connectors, and consolidation points reduce the effective channel budget.
- Temperature range −20 °C to 75 °C per TIA-568-C.2 installation and operational limits.