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RC Filter Calculator.

Calculate first-order low-pass magnitude and attenuation.

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02 / RÉPONSE

Resistance

Capacitance

Frequency

Magnitude

0,846733

Attenuation

-1,445070dB

Results update automatically as you type.

Use Cases

Analyzing signal attenuation

When you have an existing RC circuit, this calculator helps you predict how much a signal at a certain frequency will be attenuated, aiding in troubleshooting or performance analysis.

Example: Check the attenuation at a noise frequency to see if it is sufficiently reduced.

Frequently Asked Questions

What does this RC filter calculator do?: This calculator computes the magnitude (in volts per volt) and attenuation (in decibels) of a first-order low-pass RC filter at a given frequency. You input resistance (Ω), capacitance (F), and frequency (Hz), and it returns the filter's response.
How is the magnitude and attenuation calculated?: The magnitude is calculated as 1 / sqrt(1 + (2πfRC)^2), where f is frequency, R is resistance, and C is capacitance. Attenuation in dB is 20 * log10(magnitude). This calculator uses these formulas.
What is the cutoff frequency of an RC filter?: The cutoff frequency is where the magnitude drops to 0.707 (about -3 dB). It is calculated as 1 / (2πRC). This calculator does not directly compute cutoff, but you can find it by adjusting frequency until attenuation is about -3 dB.

Tips & Common Mistakes

Tips

Ensure resistance is in ohms (Ω), capacitance in farads (F), and frequency in hertz (Hz) for accurate results.
To find the cutoff frequency, adjust the frequency until the attenuation is approximately -3 dB.
Use standard resistor and capacitor values to get practical results for your circuit.
Remember that this calculator is for first-order low-pass filters; higher-order filters have different responses.

Common Mistakes to Avoid

Using microfarads (µF) instead of farads (F) without converting (1 µF = 1e-6 F).
Entering frequency in kHz instead of Hz without converting (1 kHz = 1000 Hz).
Confusing magnitude with attenuation: magnitude is a ratio (V/V), while attenuation is in dB (negative for a low-pass filter).

Last updated: August 13, 2026

Use Cases

Analyzing signal attenuation

When you have an existing RC circuit, this calculator helps you predict how much a signal at a certain frequency will be attenuated, aiding in troubleshooting or performance analysis.

Example: Check the attenuation at a noise frequency to see if it is sufficiently reduced.

Frequently Asked Questions

What does this RC filter calculator do?

This calculator computes the magnitude (in volts per volt) and attenuation (in decibels) of a first-order low-pass RC filter at a given frequency. You input resistance (Ω), capacitance (F), and frequency (Hz), and it returns the filter's response.

How is the magnitude and attenuation calculated?

The magnitude is calculated as 1 / sqrt(1 + (2πfRC)^2), where f is frequency, R is resistance, and C is capacitance. Attenuation in dB is 20 * log10(magnitude). This calculator uses these formulas.

What is the cutoff frequency of an RC filter?

The cutoff frequency is where the magnitude drops to 0.707 (about -3 dB). It is calculated as 1 / (2πRC). This calculator does not directly compute cutoff, but you can find it by adjusting frequency until attenuation is about -3 dB.

Tips & Common Mistakes

Tips

Ensure resistance is in ohms (Ω), capacitance in farads (F), and frequency in hertz (Hz) for accurate results.
To find the cutoff frequency, adjust the frequency until the attenuation is approximately -3 dB.
Use standard resistor and capacitor values to get practical results for your circuit.
Remember that this calculator is for first-order low-pass filters; higher-order filters have different responses.

Common Mistakes to Avoid

Using microfarads (µF) instead of farads (F) without converting (1 µF = 1e-6 F).
Entering frequency in kHz instead of Hz without converting (1 kHz = 1000 Hz).
Confusing magnitude with attenuation: magnitude is a ratio (V/V), while attenuation is in dB (negative for a low-pass filter).

Use Cases

Analyzing signal attenuation

When you have an existing RC circuit, this calculator helps you predict how much a signal at a certain frequency will be attenuated, aiding in troubleshooting or performance analysis.

Example: Check the attenuation at a noise frequency to see if it is sufficiently reduced.

Frequently Asked Questions

What does this RC filter calculator do?

How is the magnitude and attenuation calculated?

The magnitude is calculated as 1 / sqrt(1 + (2πfRC)^2), where f is frequency, R is resistance, and C is capacitance. Attenuation in dB is 20 * log10(magnitude). This calculator uses these formulas.

What is the cutoff frequency of an RC filter?

Tips & Common Mistakes

Tips

Ensure resistance is in ohms (Ω), capacitance in farads (F), and frequency in hertz (Hz) for accurate results.
To find the cutoff frequency, adjust the frequency until the attenuation is approximately -3 dB.
Use standard resistor and capacitor values to get practical results for your circuit.
Remember that this calculator is for first-order low-pass filters; higher-order filters have different responses.

Common Mistakes to Avoid

Using microfarads (µF) instead of farads (F) without converting (1 µF = 1e-6 F).
Entering frequency in kHz instead of Hz without converting (1 kHz = 1000 Hz).
Confusing magnitude with attenuation: magnitude is a ratio (V/V), while attenuation is in dB (negative for a low-pass filter).