Microstrip Impedance Calculator

Calculate characteristic impedance Z₀ and propagation parameters using the Hammerstad-Jensen equations.

What is this?

A microstrip is like a tiny highway for RF signals printed on a circuit board. Its width and the board's thickness determine the signal's “speed limit” — the characteristic impedance. Most RF systems need traces tuned to exactly 50 Ω so signals flow smoothly without bouncing back. Too narrow = too high impedance; too wide = too low.

Substrate & Trace Parameters
Enter physical dimensions and material properties.

The copper line width. Wider = lower impedance.

Distance from trace to ground plane. Standard FR4 is 1.6 mm.

How much the board material slows down the signal vs. air (air = 1.0). FR4 ≈ 4.4.

Standard PCB copper is 35 µm (1 oz). Thicker copper widens the effective trace slightly.

Used to calculate wavelength and propagation delay at your operating frequency.

Impedance Z₀
71.93 Ω
Effective εᵣ
3.166
Results
w/h ≤ 1
Characteristic Impedance
71.929Ω
Effective Permittivity (εe)
3.1662
w/h Ratio
0.9759
Guided Wavelength

at 2.4 GHz

70.249mm
λ/4 Length
17.562mm
Propagation Delay
5.931ps/mm
Z₀ = 71.9 Ω — for 50 Ω, try adjusting trace width. Current w/h = 0.976.

Real-world example

Every WiFi router, phone, and Bluetooth device has microstrip lines on its circuit board connecting the antenna to the radio chip. The tiny traces you see on a phone's PCB are carefully sized to hit 50 Ω — even a 10% deviation can reflect signal back and reduce range.