Measure propagation delay from trace length and substrate properties. View phase shift and velocity instantly. Use exports, formulas, tables, and graphs for design checks.
| Model | Length | Effective Er | Total Delay (ns) | Delay per mm (ps) | Wrapped Phase (deg) |
|---|---|---|---|---|---|
| Microstrip | 50 mm | 3.1153 | 0.294375 | 5.8875 | 52.9875 |
| Stripline | 3.5 in | 4 | 0.593077 | 6.6713 | 213.5077 |
| Direct Effective Dielectric | 800 mil | 2.9 | 0.115426 | 5.6804 | 103.883 |
| Microstrip | 12 cm | 2.727 | 0.661005 | 5.5084 | 285.5542 |
1. Propagation velocity = c / sqrt(effective dielectric constant).
2. Total one-way delay = trace length / propagation velocity.
3. Delay per millimeter = 0.001 / propagation velocity.
4. Delay per inch = 0.0254 / propagation velocity.
5. Phase shift = 360 × frequency × delay.
6. Guided wavelength = propagation velocity / frequency.
7. For stripline, effective dielectric constant is approximately equal to the substrate dielectric constant.
8. For microstrip, this page uses a common approximation based on width-to-height ratio to estimate the effective dielectric constant.
Trace delay helps designers estimate how long a signal needs to travel across a routed path. In digital design, that timing matters for clocks, buses, matched nets, memory interfaces, and high speed control paths. In RF and mixed signal work, the same delay also affects phase alignment and electrical length.
This calculator supports three practical modes. Microstrip mode estimates effective dielectric constant from geometry. Stripline mode assumes the field stays inside the dielectric. Direct mode lets you enter an already known effective dielectric constant from stackup data or a field solver report. That makes the page useful during both early routing and later verification.
The chart shows how total delay scales with length for the chosen propagation model. Because the relationship is linear, the graph makes it easy to compare short and long routes without recalculating every case by hand. The example table also gives quick reference values for common routing situations.
For the best engineering result, use this page as a practical estimate, then compare it against your board stackup documentation, simulation data, or measured lab results. Real delay can shift because of geometry tolerance, frequency dependence, copper roughness, and manufacturing variation.
Trace delay is the one-way travel time of a signal along a PCB path or other interconnect. Longer routes and slower propagation velocity increase the delay.
The dielectric constant changes signal velocity. A higher value slows the wave, so the same physical length creates more delay.
Microstrip runs on an outer layer and sees both air and dielectric, so its effective dielectric constant is lower. Stripline is buried, so delay is usually higher for the same length.
No. This page uses standard design approximations. Real boards can vary with stackup tolerance, roughness, copper geometry, frequency, and field solver assumptions.
Yes. Use it to compare matched or mismatched lengths. For differential pairs, run each trace or compare two lengths to estimate skew.
The calculator accepts mm, cm, m, inches, and mils. It also reports delay per millimeter, per inch, and per meter for quick routing checks.
Phase shift depends on frequency because a fixed time delay represents more degrees as the waveform cycles faster. Higher frequency means more phase rotation.
Shorten the longer route, lower unnecessary meanders, or change stackup only when design rules allow. Small length differences can still matter at fast edge rates.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.