Online Impedance Calculator
Calculate PCB trace impedance for Microstrip and Stripline configurations
Typically 4.2-4.6 for FR4
1oz Cu ≈ 0.035mm
Microstrip Model
Key Features of Impedance Calculator
Multiple Models
Support for both Microstrip and Stripline configurations to cover common PCB design needs.
Instant Calculation
Get real-time impedance results as you adjust trace width, thickness, and dielectric properties.
IPC Standards
Calculations based on standard IPC-2221 formulas for reliable and industry-accepted results.
Popular Use Cases
High-Speed Digital Design
Ensure signal integrity for USB, PCIe, DDR, and HDMI interfaces by matching trace impedance.
RF & Microwave Circuits
Design antenna feeds and RF transmission lines with precise 50Ω impedance matching.
DFM Checks
Verify if your PCB stackup and trace dimensions meet manufacturing capabilities before fabrication.
Prototype Debugging
Quickly troubleshoot signal reflection issues by validating theoretical impedance values.
How to Use the Calculator
Select Model
Choose between Microstrip (outer layer) or Stripline (inner layer) configurations.
Input Dielectric
Enter the Dielectric Constant (Er) and Thickness (H) of your PCB material (e.g., FR4).
Set Trace Dimensions
Input your designed Trace Width (W) and Copper Thickness (T).
Get Results
Click calculate to see the characteristic impedance (Zo) in Ohms.
Who Can Benefit?
- PCB Designers: Validate stackups and trace geometries.
- Electrical Engineers: Ensure signal integrity and standard compliance.
- Students & Hobbyists: Learn about transmission line theory practically.
- Purchasers: Verify specs for Controlled Impedance PCBs.
Why Users Love It
Simple & Clean Interface
No complex software to install. Just accessible, browser-based value.
Visual Aids
Clear cross-section diagrams help you understand exactly what each parameter means.
Free to Use
Professional grade calculation tool available completely for free, without registration.
Frequently Asked Questions
What is characteristic impedance?
Characteristic impedance is the ratio of voltage to current for a wave propagating along a transmission line. Matching this impedance (e.g., to 50Ω) ensures maximum power transfer and minimal signal reflection.
What dielectric constant should I use for FR4?
Standard FR4 typically ranges from 4.2 to 4.6 depending on the manufacturer and glass weave. A value of 4.2 to 4.4 is commonly used for initial calculations, but check with your PCB fabricator for precise values.
Is this calculator accurate enough for production?
This calculator uses standard IPC-2221 formulas which provide a good approximation. However, real-world impedance is affected by manufacturing tolerances, etching factors, and material variations. Always confirm the final stackup with your PCB Manufacturer (like Suntop Electronics) before production.