The cutoff frequency calculator turns capacitance (c), inductance (l), resistance (r) into cutoff frequency (fc). It suits students checking a worked example, professionals sanity-checking a figure, and anyone who wants to see how the pieces of the calculation fit together.
What Is the Cutoff Frequency Calculator?
It is built around cutoff frequency (fc), and it works the same way whether you are checking a homework answer, confirming a colleague's figure, or working something out for yourself. Everything runs in your browser, so nothing you enter is uploaded anywhere.
How the Cutoff Frequency Calculation Works
Nothing is hidden: each output is worked out from the values above it, which makes it easy to see where a surprising answer came from.
The relationship between capacitance (c), inductance (l), resistance (r) and cutoff frequency (fc), cutoff frequency (fc) is fixed, so the same figures always give the same answer. That makes it a good cross-check: run the numbers a second way and see whether the result agrees.
Getting a Result You Can Trust
The most common mistake is mixing units. Keep capacitance (c) and inductance (l) and resistance (r) in the same system throughout, and make sure any rates or ratios are quoted per the same period. When a result looks far out of range, the units are nearly always the reason.
Frequently Asked Questions
What do I need to work out cutoff frequency (fc)?
Enter capacitance (c), inductance (l), resistance (r). The calculator then works through the relationship and reports cutoff frequency (fc).
What does the cutoff frequency actually calculate?
It takes capacitance (c) and inductance (l) and resistance (r) and converts them into cutoff frequency (fc) using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter capacitance (c)?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Why does a small change in one value move the answer so much?
That happens when an output depends on a ratio, because dividing by a small number magnifies any change in it. Check the units first, then check whether the value you entered is in the range the relationship was designed for.
Can I use this for a quick estimate as well as a precise answer?
Yes. The calculator is built for quick checks, so round your inputs to a sensible number of significant figures and the result will be just as useful. If you need more precision, keep the same method and add digits to the inputs rather than adjusting the method itself.