RC filter
fc = 1 / (2 pi R C)
Electrical calculator
Cutoff Frequency Calculator
Find the -3 dB cutoff frequency for simple RC and RL filters.
Calculator
Enter values
Results update automatically as you type.
Result
About this calculator
How it works
Cutoff frequency marks the point where a filter output falls to 70.7% of its passband value. RC filters use resistance and capacitance, while RL filters use resistance and inductance.
Formulas
Formulas used
RL filter
fc = R / (2 pi L)
Guide
How to use this calculator
- Choose the mode or component type if the calculator provides one.
- Enter known values and select the units beside each input.
- Read the highlighted result first, then use the table for supporting calculated values.
Reference
What the results mean
Cutoff frequency
The frequency where output falls to about 70.7 percent of the passband value.
FAQ
Cutoff Frequency Calculator questions
Can I use different units?
Yes. Select the unit beside each input. The calculator converts values internally before solving.
Are the results suitable for final design?
Use results for education, screening, and early design checks. Verify final work against standards, datasheets, and project requirements.
Why does the result update automatically?
The calculator listens for input changes and recalculates as soon as enough valid values are available.
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