RC High-Pass Filter Calculator

This is a small-signal educational model; source/load impedance and non-ideal component behavior can change a real circuit.

Resistance

Capacitance

Probe frequency

—High-pass cutoff frequency (−3 dB point)

—Gain at probe

—Voltage ratio

—Phase

—Time constant

Electrical model check

Verify the circuit relation, units, and result

ideal first-order RC high-pass

fc = 1/(2πRC) · |H| = x/√(1+x²)

Reading the current calculator inputs…

At f = fc the ideal magnitude is 1/√2 = −3.0103 dB.

Low-voltage educational scope. This review does not provide mains wiring, live-work, conductor-sizing, protection-device, or safety-certification instructions.

RC High-Pass Filter Calculator: Bode & Tolerance Check

Analyze an RC high-pass filter with cutoff, gain, phase, Bode verification, reverse component solves and tolerance range.

Component tolerance %

Ideal first-order RC model

The calculator uses the ideal cutoff relation f_c = 1/(2πRC) plus the standard first-order transfer magnitude and phase.

Real loading changes the response

Source resistance, load impedance, capacitor ESR/tolerance and parasitics can move the measured response. Treat this as educational small-signal analysis, not safety guidance.

Governing electrical relation

fc = 1/(2πRC) · |H| = x/√(1+x²) — ideal first-order RC high-pass.

How to cross-check the result

Set probe frequency to cutoff and verify magnitude is 0.7071 and −3.0103 dB; far above cutoff approaches unity gain.

Real-component boundary

At f = fc the ideal magnitude is 1/√2 = −3.0103 dB. Component tolerance, temperature, parasitics, datasheet limits, installation rules, and hazardous-energy safety are not inferred by this idealized calculator.

Practical guide and verification

Use the product workflow above first. These notes add interpretation, verification and limits below the interactive result area.

Cutoff is the minus-3 dB point, not a brick-wall boundary

At the ideal first-order RC cutoff frequency, output magnitude is about 0.707 of the passband amplitude and phase leads by about 45 degrees. Frequencies below the corner are attenuated gradually at roughly 20 dB per decade, not removed instantly.

Evaluate gain and phase at the frequency you actually care about

A design target usually involves a signal or noise frequency, not just the corner. Compare the chosen test frequency with fc and inspect both magnitude and phase so the circuit decision reflects the operating point rather than one headline number.

Component tolerance moves the real cutoff

A 5% resistor and 10% capacitor do not produce one exact physical fc. Use the tolerance check to estimate a range, then decide whether the application has enough margin for part spread and temperature changes.

Source and load impedance can change the simple RC model

The textbook equation assumes the intended resistor dominates the impedance seen by the capacitor and that the output is not heavily loaded. Real source resistance or a low input impedance at the next stage can shift gain, phase and cutoff.

Cross-check the corner with the time constant

For an RC network, tau = R×C and fc = 1/(2πtau). Computing both ways is a useful unit check, especially when mixing ohms with kΩ or farads with nF and µF.