Signal Propagation Delay Calculator

Signal Propagation Delay Calculator. When a digital signal travels along a PCB trace, it doesn't arrive instantaneously — the Signal Propagation Delay Calculator tells you exactly how long that journey takes based on your board's physical and material properties. Enter your trace length, select a dielectric material (FR-4, PTFE, Rogers, and more), and choose a trace structure (microstrip or stripline) to calculate the propagation delay in picoseconds. Secondary outputs include signal velocity, delay per inch, and the effective dielectric constant used in the calculation. Also try the calculate RMS Phase Jitter, RMS Jitter (seconds) & RMS Jitter (radians) — Phase Noise to Jitter.

Results

Propagation Delay

Signal Velocity

Delay per Inch

Effective Dielectric Constant

What is signal propagation delay?

Signal propagation delay is the time it takes for an electrical signal to travel from one point to another along a PCB trace or transmission line. It's determined by the trace length and the speed at which signals travel through the dielectric material. See also our Signal-to-Noise Ratio (SNR) Calculator.

How do you calculate propagation delay?

Propagation delay is calculated using the formula: Delay = Distance / Signal Velocity. The signal velocity depends on the dielectric constant of the PCB material and trace structure (microstrip or stripline).

Why does propagation delay matter in PCB design?

Propagation delay is critical for high-speed digital circuits because timing mismatches between signals can cause setup and hold violations, signal integrity issues, and circuit malfunction. Managing delay is essential for synchronous systems.

What affects signal velocity on a PCB?

Signal velocity is primarily affected by the dielectric constant of the PCB material and the trace structure. Lower dielectric constants result in faster signal propagation, while higher values slow down the signal. You might also find our Rise Time — Rise Time / Fall Time useful.

What's the difference between microstrip and stripline delay?

Microstrip traces (on surface layers) typically have slightly higher signal velocity than stripline traces (between ground planes) due to the air interface reducing the effective dielectric constant.

How accurate are PCB propagation delay calculations?

Theoretical calculations provide good estimates, but actual delays can vary by ±10-15% due to manufacturing tolerances, trace geometry variations, and temperature effects. For critical timing, measurement verification is recommended.

What materials have the lowest propagation delay?

Air and air-spaced dielectrics have the lowest propagation delay due to their low dielectric constants. PTFE-based materials also offer good high-speed performance with relatively low delay compared to standard FR-4.