Controlled-impedance design for microstrip, stripline, CPWG and differential pairs — in your browser
Open the ToolControlled impedance is where high-speed and RF boards are won or lost, yet most quick calculators only do one geometry, ignore frequency dispersion, and quietly disagree with each other by several percent.
The Salitronic PCB Impedance Calculator covers nine transmission-line geometries with the same literature-validated physics engine, solves either direction (width from a target impedance, or impedance from a width), and reports the full picture: effective permittivity, conductor and dielectric loss, phase velocity, guide wavelength and propagation delay — with a live cross-section that updates as you type. It runs entirely in your browser; nothing is uploaded.
Pick a line type, set your stackup, read the geometry. No signup, no install.
Launch PCB Impedance CalculatorSurface microstrip using the Hammerstad-Jensen quasi-static model with Kirschning-Jansen frequency dispersion and conductor-thickness correction. Embedded / buried microstrip blends the effective permittivity toward the bulk value as the dielectric cover thickens (IPC-2141 form).
Symmetric stripline via the exact Cohn conformal-mapping result with complete elliptic integrals. Asymmetric (offset) stripline models the trace's capacitance to each plane as a parallel combination, reducing exactly to the symmetric case when centered.
Grounded coplanar waveguide (CPWG) and ungrounded CPW using the Ghione/Simons elliptic-integral formulation with the lower-ground modulus and finite-substrate correction. The h → ∞ limit reduces to the textbook half-space CPW.
Edge-coupled microstrip uses the rigorous Hammerstad-Jensen even/odd coupling functions. Edge-coupled and broadside-coupled stripline pairs are supported too, reporting odd-, even-, differential- and common-mode impedance.
Conductor loss from the skin effect with a Hammerstad-Jensen surface-roughness correction, dielectric loss from the loss tangent, total loss in dB/m and over your trace length, plus phase velocity, guide wavelength and propagation delay.
FR-4 and Rogers presets or fully custom dielectrics. Optional solder-mask superstrate (calibrated to the ~5 % drop board houses see) and trapezoidal trace-etching via an etch factor, with the effective (mean) width fed into the impedance model.
A scaled cross-section redraws on every change, showing the trace (trapezoid when etch is enabled), dielectric, reference plane(s), solder mask and the W, S/gap and H/b dimensions for the selected geometry.
Enter a target impedance and get the trace width, or enter a width and get the impedance. Results update live, and you can copy the full result set as JSON for your design notes.
The physics core is compiled to WebAssembly and runs in your browser. Your stackup and geometry never leave your machine, and there is no signup or install.
The physics core ships with an automated test suite that checks every model against independent published references and exact limiting cases, not just internal consistency:
| Model | Reference / check |
|---|---|
| Microstrip Z0 & εeff | Hammerstad-Jensen worked examples (e.g. 50.6 Ω / εeff 2.73) |
| Dispersion | Kirschning-Jansen (QUCS reference), εeff ≈ 3.47 at 10 GHz on FR-4 |
| Stripline | Exact Cohn elliptic-integral value (W/b = 0.5 → 48.5 Ω) |
| CPWG / CPW | Half-space limit = textbook CPW (77.3 Ω / εeff 2.70) |
| Differential microstrip | Hammerstad-Jensen coupled (Z0e 59 Ω / Z0o 37 Ω) |
| Conductor / dielectric loss | Pozar closed forms (2.564 dB/m at 20 GHz) |
Closed-form models carry an inherent few-percent error versus full-wave EM simulation; for tight tolerances, confirm critical nets with a field solver or a measured coupon.
Microstrip, embedded/buried microstrip, symmetric stripline, asymmetric (offset) stripline, grounded coplanar waveguide (CPWG), coplanar waveguide without ground, and edge-coupled and broadside-coupled differential pairs.
Hammerstad-Jensen for microstrip with Kirschning-Jansen frequency dispersion, the exact Cohn conformal-mapping result for stripline, Ghione/Simons elliptic-integral formulas for CPW and CPWG, and Wadell/Hammerstad-Jensen coupled-line models for differential pairs.
Each model is checked against published reference values and exact limiting cases in an automated test suite. Like all closed-form tools, expect a few-percent spread versus a full-wave field solver; the surface-microstrip and stripline cases are the most accurate, the coupled and offset geometries are engineering approximations.
Yes. Enable the solder-mask superstrate (calibrated to the typical ~5 % impedance drop) and the trapezoidal etch model, which feeds the effective (mean) trace width into the impedance calculation and draws the true trapezoid in the cross-section.
Yes — conductor loss (skin effect plus roughness), dielectric loss, total loss in dB/m and over your trace length, phase velocity, guide wavelength and propagation delay.
No. Everything runs locally in your browser via WebAssembly. Nothing leaves your machine.