Microstrip impedance calculator
Calculate impedance and effective permittivity from your PCB geometry.
Impedance Z0 (ohm): 50.17
| Impedance Z0 (ohm) | 50.17 |
|---|---|
| Effective permittivity | 3.301 |
| Wheeler width, zero thickness (mm) | 3.051 |
| H-J target width with thickness (mm) | 3.017 |
| H-J impedance at Wheeler width (ohm) | 49.67 |
A microstrip line with width 3 mm, substrate height 1.6 mm, conductor thickness 0.035 mm and relative permittivity 4.4 has about 50.2 ohm impedance. Enter your geometry to calculate impedance, effective permittivity and a width for a target impedance.
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https://scienceshot.com/mcpConnector tool: microstrip_impedance
Example: What is the impedance of a 3 mm microstrip on a 1.6 mm substrate with er 4.4 and 0.035 mm conductor thickness?
Wheeler (1977) synthesis numerically inverts his zero-thickness expression. Its width is approximate for this model; the separate thickness-corrected H-J target width solves Z0(w)=Ztarget.
50 ohm input examples
All rows use h = 1.6 mm and t = 0.035 mm.
| Input example | Relative permittivity er | H-J target width with thickness (mm) | Effective permittivity |
|---|---|---|---|
| FR-4 input example | 4.3 | 3.06955 | 3.24036 |
| FR-4 input example | 4.5 | 2.96591 | 3.36438 |
| RO4350B process Dk | 3.48 | 3.58222 | 2.72257 |
| RO4350B design Dk | 3.66 | 3.45541 | 2.83763 |
Cite this
ScienceShot. Microstrip impedance calculator. https://scienceshot.com/microstrip-impedance-calculator.
More formats
ScienceShot. (2026). Microstrip impedance calculator [Online calculator]. https://scienceshot.com/microstrip-impedance-calculator
@misc{scienceshot-microstrip-impedance-calculator-2026,
author = {{ScienceShot}},
title = {{Microstrip impedance calculator}},
year = {2026},
note = {Online calculator},
url = {https://scienceshot.com/microstrip-impedance-calculator}
}Sources: Hammerstad and Jensen (1980), IEEE MTT-S Digest; Wheeler (1977), IEEE T-MTT; Rogers RO4000 datasheet: process 3.48, design 3.66 (accessed 2026-11-06); NIST CODATA 2018 (2021).
Reviewed by a physicist with CERN experience