Online Impedance Calculator
Calculate PCB trace impedance for Microstrip and Stripline configurations
Online Impedance Calculator
Estimate single-ended trace impedance for microstrip and stripline routing, then use the result as an early design and manufacturing review reference.
Typically 4.2-4.6 for FR4
1oz Cu ≈ 0.035mm
Microstrip Model
When to use this calculator
Use it during stackup and routing decisions when you need a fast estimate of single-ended impedance for outer or inner layer traces.
Check whether your chosen dielectric thickness and trace width are directionally close to a target impedance before final fabrication review.
Use it as a starting point when discussing stackup, material, and impedance control capability with your PCB manufacturer.
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.
Related resources & next steps
Review dielectric constant assumptions when material selection has a strong effect on impedance targets.
Check trace width from a current-carrying perspective after reviewing impedance targets.
Move from approximate impedance math to a production-ready stackup and controlled impedance review.
Send your target impedance, stackup assumptions, and fabrication goals to our engineering team.
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.
Need help turning target impedance into a manufacturable stackup?
If you are working on high-speed or RF routing, we can help review dielectric choices, copper thickness, trace geometry, and controlled impedance feasibility before production.