Definitions for common inductor parameters

January 9, 2020The SnapEDA Team

Inductors are common, two-terminal electrical devices that store energy in a magnetic field. They’re typically made from a simple coil of wire, wound around either a metal or air core. They are commonly used in filters, transformers, tuning circuits, energy storage, impedance matching, sensors and more.

The most important step when selecting an inductor is to understand and consider your specific application. From there, you’ll want to consider parameters such as inductance, tolerance, and DC resistance to ensure maximal performance and efficiency of your design.

In this blog, we will explore the main parameters of inductors, their definitions and tips to help you choose the right one!

Inductor Parameters

1) Quality Factor (Q)

The Quality Factor is the ratio of the reactance of the inductor to its resistance. Inductors are not purely inductive, and their resistance causes energy loss which can limit its performance. Hence, the higher the Q factor, the lower the rate of energy loss.

2) Self-Resonant Frequency or SRF

The low distributed capacitance between inductor terminals causes inductors to have a self-resonant frequency (SRF). The SRF is the frequency at which an inductor stops working as an inductor. Designers should select an inductor with an SRF that is higher than the operating frequency.

3) Saturation Current

The saturation current is the current value at which the conductor can not take in any more magnetic flux. At this point, the inductance will drop at a specified value. Like the SRF, the saturation current must be significantly higher than the maximum current that will pass through the inductor.

4) DC Resistance

The DC resistance (DCR) is the resistance component of the coil. A high DCR will cause high losses, so it is always better to select an inductor with low DCR value. It is important to consider the acceptable DCR of the inductor according to your application.

5) Tolerance

Tolerance indicates how much the inductance can vary from the nominal value. This information is usually found in the component’s datasheet. Tolerances in general are not desired, but are inversely proportional with cost. Therefore, this parameter should be ultimately selected based on your application.


We hope that this blog helped you to understand some of the basic parameters to consider when selecting an inductor to use in your next PCB project! Be sure to explore SnapEDA’s free inductor schematic symbols, PCB footprints, and 3D models next.

If you have any comments or questions, feel free to add them in the comment section. Until then, happy designing!

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