Stripline Impedance Calculator

Embedded PCB Stripline Impedance Estimator

Input Fields

Dielectric Constant

εr

Relative permittivity of the substrate

Trace Width

W

mm

Width of the stripline trace

Copper Thickness

T

mm

Thickness of the copper trace

Dielectric Height

H

mm

Distance to the ground plane (half of total substrate height)

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Your Results

Characteristic Impedance

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Stripline Characteristic Impedance Formula

$$Z_0 = \frac{60}{\sqrt{\varepsilon_r}} \cdot \ln\left( \frac{0.67 \pi (W + T)}{4H} \right)$$

Where:

• $$Z_0$$ = characteristic impedance (Ω)
• $$\varepsilon_r$$ = dielectric constant of substrate
• $$W$$ = trace width (mm)
• $$T$$ = trace thickness (mm)
• $$H$$ = distance from trace center to each ground plane (mm)

This equation assumes symmetrical stripline configuration with uniform dielectric.

Stripline Impedance – Calculation Example

Given:

• $$\varepsilon_r$$ = 4.3
• $$W$$ = 0.2 mm
• $$T$$ = 0.035 mm
• $$H$$ = 0.3 mm

Calculation:

1. $$Z_0 = \frac{60}{\sqrt{4.3}} \cdot \ln\left( \frac{0.67 \cdot \pi \cdot (0.2 + 0.035)}{4 \cdot 0.3} \right)$$
2. $$≈ \frac{60}{2.0736} \cdot \ln\left( \frac{0.67 \cdot \pi \cdot 0.235}{1.2} \right)$$
3. $$≈ 28.93 \cdot \ln(0.412) ≈ 28.93 \cdot (-0.886) ≈ -25.64~\Omega$$

Stripline transmission lines are used in high-frequency multilayer PCBs where the signal trace is enclosed between two ground planes. This structure provides excellent shielding and consistent impedance. The calculator is ideal for RF and high-speed PCB designers who require precise impedance control to avoid signal reflections, maintain signal integrity, and comply with design rules.