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RC high-pass filter
Estimate the cutoff and voltage attenuation of an ideal first-order passive RC high-pass filter.
Resistance (Ω): 1–10000000; Capacitance (µF): 0.000001–10000; Signal frequency (Hz): 0.1–1000000
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RC high-pass filter
Resistance (Ω): 10000 Capacitance (µF): 0.1 Signal frequency (Hz): 100
- Cutoff frequency (Hz)
- 159.154943
- Voltage level change (dB)
- -5.481473
Use a series capacitor followed by a shunt resistor, with output measured across the resistor. Convert capacitance from µF to F by multiplying by 0.000001. Cutoff fc = 1 / (2πRC); amplitude ratio = f / √(f² + fc²); voltage level change = 20 log10(ratio). At cutoff the change is −3.010300 dB, not zero. Enter R 1–10,000,000 Ω, C 0.000001–10,000 µF and signal frequency 0.1–1,000,000 Hz, including fractions. This small-signal model assumes an ideal voltage source, ideal components and no additional output load. Source resistance, input loading, component tolerance and parasitics can alter the response. It does not model an arbitrary mixer high-pass setting, a digital filter, a multi-pole crossover, phase or a loudspeaker load. Use it to compare an ideal coupling/filter network, then verify the actual circuit and frequency response. It is not a construction or wiring specification. Display uses six decimals without intermediate rounding.
Methodology
How it works
Use a series capacitor followed by a shunt resistor, with output measured across the resistor. Convert capacitance from µF to F by multiplying by 0.000001. Cutoff fc = 1 / (2πRC); amplitude ratio = f / √(f² + fc²); voltage level change = 20 log10(ratio). At cutoff the change is −3.010300 dB, not zero. Enter R 1–10,000,000 Ω, C 0.000001–10,000 µF and signal frequency 0.1–1,000,000 Hz, including fractions. This small-signal model assumes an ideal voltage source, ideal components and no additional output load. Source resistance, input loading, component tolerance and parasitics can alter the response. It does not model an arbitrary mixer high-pass setting, a digital filter, a multi-pole crossover, phase or a loudspeaker load. Use it to compare an ideal coupling/filter network, then verify the actual circuit and frequency response. It is not a construction or wiring specification. Display uses six decimals without intermediate rounding.
Method and assumptions documented by Techrider.live
2026-10-30
Frequently asked questions
Is this the same as filter bandwidth or Q?
No. This tool predicts an ideal one-pole RC high-pass response from physical R and C values. The bandwidth/Q tool describes an existing band from its edge frequencies; it does not predict this circuit.