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RC low-pass cutoff calculator
Calculate the time constant and cutoff frequency of a first-order RC low-pass filter, whose cutoff has approximately 70.7% of the input voltage amplitude.
On this page
Cutoff frequency159.15Hz
Time constant1.00e-3s
Calculator controls
How to calculate
Calculate the time constant and cutoff frequency of a first-order RC low-pass filter, whose cutoff has approximately 70.7% of the input voltage amplitude.
Cutoff frequency = 1/(2*pi*r*c/1000000) Hz; Time constant = r*c/1000000 s
Worked example
Resistance (Ω): 1000; Capacitance (µF): 1.
Cutoff frequency: 159.15 Hz; Time constant: 1.00e-3 s.
Assumptions and limits
Calculate the time constant and cutoff frequency of a first-order RC low-pass filter, whose cutoff has approximately 70.7% of the input voltage amplitude. Ideal components without parasitic effects or losses. Reactance is a magnitude for sinusoidal AC. The RC cutoff assumes an unloaded first-order low-pass filter.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
Calculate the time constant and cutoff frequency of a first-order RC low-pass filter, whose cutoff has approximately 70.7% of the input voltage amplitude.
When this tool is useful
Cutoff frequency = 1/(2*pi*r*c/1000000) Hz; Time constant = r*c/1000000 s
Understanding your inputs
| Input | What to enter |
|---|---|
| Resistance (Ω) | Enter a number of at least 1e-12 and no more than 1000000000000. |
| Capacitance (µF) | Enter a number of at least 1e-12 and no more than 1000000000000. |
Frequently asked questions
What assumptions does this calculation use?
Calculate the time constant and cutoff frequency of a first-order RC low-pass filter, whose cutoff has approximately 70.7% of the input voltage amplitude. Ideal components without parasitic effects or losses. Reactance is a magnitude for sinusoidal AC. The RC cutoff assumes an unloaded first-order low-pass filter.
How is the result calculated?
Cutoff frequency = 1/(2*pi*r*c/1000000) Hz; Time constant = r*c/1000000 s