Inductor codes

Formulas, limitations and content checked according to our Editorial method.

Read the 3-digit codes of SMD inductors as 100, 101 o 221 and do the reverse conversion from µH/mH to the code.

3-digit codes µH / mH / H Inductive reactance

Code → value

Inductor code

Tolerance (optional)

Frequency for XL (kHz, optional)

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101

10 followed by 1 zero in µH: 100 µH.

220

22 followed by 0 zeros: 22 µH. It's not 220 µH, because that would be too easy to live with.

Real notes

The code is not enough to choose an inductor: look at saturation current, DCR and working frequency.

What is inductive reactance?

XL = 2π × f × L. Increases with frequency. At DC, an inductor is just a resistive wire.