Please enter all required values.
RESULTS
Input Parameters Specification
Trace ThicknessCopper trace thickness used for effective width correction. Thicker copper can shift RF microstrip impedance from the ideal thin-conductor estimate.
Substrate HeightDielectric height between the microstrip trace and ground plane. This is one of the most important PCB stack-up dimensions.
Trace WidthTop copper conductor width used in impedance calculation. Wider microstrip traces usually reduce characteristic impedance.
Dielectric ConstantRelative permittivity of PCB substrate material. FR4, Rogers, PTFE and ceramic laminates can produce different impedance values.
Practical Operational Examples
50 Ω RF Trace
Design controlled impedance microstrip routing for RF modules, antennas, filters, matching networks and high-speed signals.
PCB Stackup Check
Adjust width, height, copper thickness and dielectric constant to match required impedance before fabrication.
Wireless Hardware
Estimate trace impedance for Wi-Fi, GPS, Bluetooth, LoRa, RF front-end and microwave PCB routing.
Prototype Debugging
Compare calculated impedance with measured RF performance when a feedline, antenna section or matching network behaves incorrectly.
Diagrams & Theory
A microstrip trace sits on top of the PCB dielectric with a reference ground plane below. Its impedance depends on trace width, copper thickness, substrate height and dielectric constant. Because part of the electromagnetic field travels through air and part through dielectric, microstrip impedance is sensitive to PCB material, geometry and manufacturing tolerance.
Formulas & Mathematical Logic
Step 1: Convert trace thickness, substrate height and trace width using the selected unit multipliers.
Step 2: The calculator preserves your supplied microstrip impedance JavaScript formula and unit multipliers.
Step 3: Effective trace width is corrected using copper thickness, trace width, substrate height and dielectric constant.
Step 4: Impedance is calculated using the microstrip transmission line expression from the original source code.
Step 5: The result is displayed as impedance in ohms, and the entered dielectric constant is shown for confirmation.
Practical meaning: wider traces usually reduce impedance, while taller substrate height usually increases impedance.
Step-by-Step Example
Example: trace thickness = 1 mil, substrate height = 62 mil, trace width = 120 mil, dielectric constant = 4.4.
The calculator converts all geometry inputs into the units expected by the original formula.
Copper thickness is used to correct the effective trace width.
The dielectric constant is applied to the microstrip transmission line equation.
The calculated result gives approximate microstrip characteristic impedance in ohms.
For RF design, compare this value with the target impedance such as 50 Ω before final PCB routing.
How to Use This Calculator
Enter copper trace thickness and choose the correct unit.
Enter substrate height from trace layer to reference ground plane.
Enter microstrip trace width.
Enter dielectric constant of the PCB material.
Click Calculate to get microstrip impedance and confirm dielectric constant.
Use the result to adjust trace width or stack-up before PCB fabrication.
About This Calculator
Estimate microstrip impedance for RF and controlled-impedance PCB routing.
The CalcBoy Microstrip Impedance Calculator calculates PCB trace impedance from copper thickness, substrate height, trace width and dielectric constant.
Microstrip routing is one of the most common transmission line structures in RF and high-speed PCB design. A microstrip trace sits on an outer PCB layer with a reference ground plane below it. This geometry is used for RF modules, antenna feeds, matching networks, filters, clock lines, wireless boards and controlled-impedance digital signals.
The impedance of a microstrip trace depends strongly on trace width, dielectric height, copper thickness and dielectric constant. If the trace is too narrow or too wide, the impedance can move away from the target value such as 50 Ω. That mismatch may cause reflection, poor return loss, reduced RF power transfer, antenna tuning issues or signal integrity problems.
This calculator is useful for early PCB stack-up planning, RF prototype work, antenna feed routing and impedance comparison. For final production, always confirm results with your PCB manufacturer because solder mask, copper plating, dielectric tolerance, glass weave and laminate variation can shift the real impedance.
Best UseMicrostrip impedance checks for RF PCB and controlled-impedance routing.
Supported InputsTrace thickness, substrate height, trace width and dielectric constant.
Helpful ForRF feeds, antennas, filters, Wi-Fi, GPS, Bluetooth, LoRa and high-speed signals.
Design ReminderUse real stack-up data from the PCB manufacturer for final impedance control.
Tip: For a 50 Ω RF trace, do not guess the width only from old boards. Use the actual dielectric height and material data from your PCB stack-up.
Frequently Asked Questions
What is microstrip impedance?
Microstrip impedance is the characteristic impedance of a PCB trace routed on an outer layer over a reference ground plane.
What affects microstrip impedance?
Trace width, copper thickness, substrate height and dielectric constant all affect the calculated impedance.
Does wider trace lower impedance?
Yes. Increasing trace width generally lowers microstrip impedance.
Can this calculate 50 ohm RF trace width?
This calculator calculates impedance from a given width. You can adjust width and recalculate until the result is near 50 Ω.
Is FR4 dielectric constant fixed?
No. FR4 dielectric constant can vary by supplier, frequency and laminate construction, so use real material data when possible.
Is microstrip the same as stripline?
No. Microstrip is on an outer layer above a reference plane, while stripline is embedded between two reference planes.
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