Please enter all required values.
RESULTS
Input Parameters Specification
Trace ThicknessCopper thickness of the embedded asymmetric stripline trace. Thickness affects effective conductor geometry and impedance correction.
Height 1Distance from the trace to one reference plane. This lower or first dielectric height shifts impedance when the trace is off-center.
Height 2Distance from the trace to the other reference plane. Different H1 and H2 values create asymmetric stripline behavior.
Trace WidthWidth of the embedded conductor. Wider traces generally reduce characteristic impedance.
Dielectric ConstantRelative permittivity of the PCB material. Higher dielectric constant normally lowers stripline impedance.
OutputCalculated asymmetric stripline impedance in ohms for RF PCB and controlled-impedance stackup checks.
Practical Operational Examples
Multilayer PCB Stackup
Estimate impedance when the stripline trace is not centered between top and bottom reference planes.
Controlled Impedance
Change H1, H2, trace width and dielectric constant to tune a target impedance for RF or high-speed routing.
Manufacturing Review
Use the result as an early estimate before confirming the exact layer geometry with your PCB manufacturer.
RF Layout Debugging
Check how off-center dielectric spacing may shift impedance from a symmetric stripline assumption.
Diagrams & Theory
An asymmetric stripline has a trace located closer to one reference plane than the other. Because H1 and H2 are different, impedance shifts compared with a symmetric stripline.
Formulas & Mathematical Logic
The calculator preserves the supplied asymmetric stripline impedance JavaScript logic and unit multipliers.
Step 1: Convert trace thickness, H1, H2 and trace width using the selected unit multipliers.
Step 2: Average height = (H1 + H2) / 2.
Step 3: A symmetric stripline estimate is calculated at average height with dielectric constant set to 1.
Step 4: Separate symmetric stripline estimates are calculated for H1 and H2.
Step 5: Parallel impedance term = 2 × (Z1 × Z2 / (Z1 + Z2)).
Step 6: A correction factor is applied based on H1, H2, trace thickness and trace width.
Step 7: Final impedance = (average impedance - correction) / sqrt(dielectric constant).
Step-by-Step Example
Example: trace thickness = 1 mil, H1 = 8 mil, H2 = 20 mil, trace width = 10 mil, dielectric constant = 4.2.
The calculator converts all geometric inputs using the selected unit multipliers.
It calculates the average of H1 and H2 to build a baseline symmetric stripline value.
It separately evaluates the trace relative to H1 and H2.
The asymmetry correction is applied using the original source expression.
The result is scaled by dielectric constant and displayed as impedance in ohms.
How to Use This Calculator
Enter the embedded trace copper thickness and choose the unit.
Enter Height 1 from the trace to one reference plane.
Enter Height 2 from the trace to the other reference plane.
Enter trace width and select the correct unit.
Enter dielectric constant of the PCB laminate.
Click Calculate to get asymmetric stripline impedance.
About This Calculator
Estimate impedance when a stripline trace is not centered between planes.
The CalcBoy Asymmetric Stripline Impedance Calculator calculates characteristic impedance from trace thickness, H1, H2, trace width and dielectric constant.
In many multilayer PCB stackups, a stripline trace is not perfectly centered between the two reference planes. One dielectric thickness may be smaller than the other because of available prepreg, core thickness, routing layer choice or manufacturing stackup. That structure is called an asymmetric stripline, and its impedance can be different from a standard centered stripline calculation.
This calculator is useful for RF PCB routing, microwave boards, high-speed digital nets, controlled impedance traces and stackup planning. Instead of assuming equal distance above and below the trace, it lets you enter H1 and H2 separately, making it more practical for real PCB layer structures.
Use this result for early design and comparison. For production controlled-impedance work, confirm the final value with your PCB manufacturer because copper plating, dielectric tolerance, resin content, glass weave and lamination process can shift the real impedance.
Best UseOff-center stripline impedance checks for multilayer PCB stackups.
Supported InputsTrace thickness, H1, H2, trace width and dielectric constant.
Helpful ForRF traces, high-speed signals, controlled impedance nets and stackup review.
Design ReminderUse manufacturer stackup data for final impedance control.
Tip: If H1 and H2 are very different, do not use a symmetric stripline calculator. Use this asymmetric version for a closer estimate.
Frequently Asked Questions
What is asymmetric stripline impedance?
It is the characteristic impedance of a stripline trace that is not centered between two reference planes.
What are H1 and H2?
H1 and H2 are the two different dielectric distances from the trace to the reference planes.
Why does asymmetry change impedance?
Because the electromagnetic field is not evenly distributed above and below the trace when the reference plane distances are different.
Can I use this for RF PCB design?
Yes. It is useful for RF and high-speed PCB stackups where the trace is off-center.
Does dielectric constant affect the result?
Yes. Higher dielectric constant generally lowers the impedance value.
Can this replace PCB manufacturer impedance control?
No. Use it as an estimate and verify final values with your PCB manufacturer’s controlled-impedance stackup.
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Wire Stripline Impedance CalculatorCalculate impedance for round wire stripline geometry.