Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.

Trace Length (m) (m)

Required number input.

Effective Permittivity

Required number input.

Estimate PCB trace flight time as length times √εeffective divided by the speed of light; use the trace geometry's effective dielectric constant. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Propagation Delay (s) (s)

The resulting propagation delay (s) returned as a number.

• Signal-integrity estimates depend on edge rate, channel loss, impedance discontinuities, termination, encoding, equalization, clock recovery, jitter decomposition, crosstalk, connectors, vias, and receiver masks. Aggregate budgets must use compatible statistical or worst-case conventions.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.

• PCB Trace Length From Delay

  Calculate PCB trace length from measured or budgeted flight time and effective dielectric constant using speed c/√εeffective.

• Ethernet Cable Propagation Delay

  Estimate one-way signal propagation delay from cable length and velocity factor relative to light speed. Actual velocity factor depends on cable construction; this does not include switch or PHY latency.

• SPI Frequency from Trace Delay

  Estimate a conservative SPI clock ceiling from trace length, propagation delay per metre, and available timing fraction of a cycle. This only budgets propagation delay; include device clock-to-output, setup, skew, and return path in a real design.