How this calculator works
For a non-magnetic homogeneous dielectric, phase velocity is approximately the vacuum speed of light divided by the square root of relative permittivity. Multiply distance by delay per metre to get one-way travel time. Material presets are nominal examples; foamed and air-spaced cables depend strongly on construction. Use the cable datasheet velocity factor for accurate timing.
Formula
v = c/sqrt(er); velocity factor = 1/sqrt(er); t = d/v; c = 299792458 m/s.
Worked example
With relative permittivity 2.25, velocity factor is 2/3. A 100 m cable has about 500.346 ns of one-way delay; the return trip doubles it.
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Frequently asked questions
Is this the total network latency?
No. Transmission, switching, queuing and software delays must be added.
How do I enter a datasheet velocity factor?
Choose custom relative permittivity and enter 1 divided by the square of the velocity factor.
Are nanoseconds an input unit?
The current engine accepts seconds; enter scientific notation such as 5e-7 for 500 ns. A separate output shows ns.