Impedance Calculator

Calculate the impedance of an AC circuit with the Impedance Calculator and learn on the go with the integrated live example

The DC resistance of a length of wire may be very small, but the effective resistance can be very high when the length of wire is powered with an AC signal. This is called the impedance.

The formula to calculate impedance is:

$Z=\sqrt{R^2 + X^2}$

Where
Z = Impedance in ohms
R = Resistance in ohms
X = The total reactance in ohms = X_L – X_C

Example: Find the impedance of a coil with a wire resistance of 2.3 ohms and reactance of 5000 ohms

$Z=\sqrt{2.3^2+5000^2}=\sqrt{5.29+25000000}$

$=\sqrt{25000005.29}$

$Z=5000.001\; ohms$

Using the Impedance Calculator

Resistance: Input the resistance and select your preferred units

Reactance: Input the total reactance and select your preferred units

Selecting units: You can choose your preferred units of measurement through selecting the units cells and clicking the downwards pointing arrow to display a list of available options

Learn As You Go: This feature displays a live example of how to calculate impedance using the figures that you enter

Reference: ARRL – The Radio Amateur’s Handbook