RC High-Pass Cutoff Calculator
An RC high-pass filter does the opposite of a low-pass: it passes high-frequency signals while attenuating low-frequency ones, which makes it useful for blocking DC offsets and removing slow drift from a signal. Like its low-pass counterpart it is built from a single resistor and capacitor, and its cutoff frequency, the three-decibel point, is set by the same expression: one divided by two pi times the resistance times the capacitance. Below the cutoff, low frequencies are increasingly blocked; above it, signals pass freely. A larger resistor or capacitor lowers the cutoff, widening the band of frequencies that get through. This calculator takes the resistance in ohms and the capacitance in farads and returns the cutoff frequency in hertz to two decimal places. Enter the capacitance in farads, so a 10 nanofarad part is 0.00000001 farads. The formula is the standard corner-frequency relation for a first-order RC stage, identical in form to the low-pass case but applied to a high-pass arrangement. The definitions of the ohm, the farad and the hertz are maintained by the National Institute of Standards and Technology. Every figure here is computed deterministically from the formula, shown in full below, with a worked example that reconciles exactly to the calculator so you can check each step yourself.
The RC high-pass cutoff frequency is f = 1 / (2 pi R C). With 1,000 ohms and 10 nF (0.00000001 F), the cutoff is 15,915.49 Hz. A larger R or C lowers the cutoff.
RC high-pass cutoff formula
f = 1 / (2 pi R C)
f = cutoff (corner) frequency (Hz)
R = resistance (ohms)
C = capacitance (farads)
Multiply the resistance by the capacitance for the RC time constant, multiply by two pi, then take the reciprocal. The result is the frequency at which the filter's output power has dropped to half (3 dB down). Below this frequency low-frequency signals are attenuated; above it they pass.
Worked example
An RC high-pass filter uses a 1,000 ohm resistor and a 10 nF capacitor, which is 0.00000001 farads.
- Multiply R by C: 1,000 x 0.00000001 = 0.00001
- Multiply by 2 pi: 2 x 3.14159265 x 0.00001 = 0.0000628319
- Take the reciprocal: 1 / 0.0000628319 = 15,915.49
- The cutoff frequency is 15,915.49 Hz
So the high-pass filter's cutoff is about 15,915.49 Hz. These are the calculator's default inputs, so the result above matches the widget exactly.
RC High-Pass Cutoff Calculator: frequently asked questions
How do you calculate an RC high-pass cutoff frequency?
Use f = 1 / (2 pi R C), the same form as the low-pass case. With R = 1,000 ohms and C = 10 nF, the cutoff is 1 / (2 pi x 1,000 x 0.00000001) = 15,915.49 Hz. Frequencies above the cutoff pass; lower ones are attenuated.
Why is the formula identical to the low-pass filter?
Both are first-order RC networks with the same time constant R times C, so they share the same corner frequency. What differs is the circuit topology: swapping the positions of the resistor and capacitor turns a low-pass into a high-pass while keeping the cutoff the same.
What is a high-pass filter used for?
High-pass filters block DC and slow drift while letting faster signals through. They are used as coupling capacitors between amplifier stages, to remove offset from sensor signals, and to separate treble in audio crossovers.
How do I convert capacitor units to farads?
One microfarad is 0.000001 F, one nanofarad is 0.000000001 F and one picofarad is 0.000000000001 F. So 10 nF equals 0.00000001 F, the value used in this example.
What is the RC high-pass cutoff formula?
The corner frequency is f = 1 / (2 pi R C), identical in form to the low-pass filter.
Official sources
- Electrical units and measurement standards: US National Institute of Standards and Technology (NIST). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.