Electrical and electronics
Capacitive and inductive reactance and resonant frequency calculator
Capacitive reactance 1/(2πfC), inductive reactance 2πfL, LC resonant frequency, characteristic impedance and series Q.
Runs in your browser. What you enter stays on this page and is not uploaded.
Showing the worked example. Results update as you type.
Result
Method and limits
At frequency f a capacitor has reactance XC = 1 / (2π f C) and an inductor XL = 2π f L. They are equal at the resonant frequency f0 = 1 / (2π √(L C)), where a series LC circuit has zero net reactance and a parallel one is at maximum impedance. √(L/C) is the characteristic impedance; for a series RLC circuit Q = √(L/C) / R and the −3 dB bandwidth is f0 / Q.
Worked example: at 1 kHz, 1 µF has XC = 159.2 Ω and 10 mH has XL = 62.83 Ω; together they resonate at 1.592 kHz.
Limits
Ideal components: real capacitors have series inductance and resistance and real inductors self-capacitance, which move resonance and limit Q at high frequencies.
References
Related tools
- Ohm’s law and power calculatorEnter any two of voltage, current, resistance and power to get the other two, with SI prefixes such as mA, kΩ and µW.
- Resistor colour code calculator (4, 5 and 6 band)Read a 4-, 5- or 6-band resistor colour code, or find the bands for a value, with tolerance, temperature coefficient and the nearest E-series value.
- Voltage divider calculatorCalculate the output of a two-resistor voltage divider with or without a load, or find the bottom resistor for a target voltage with the nearest E24 and E96 values.
- LED series resistor calculatorFind the series resistor for one LED or a string of LEDs from the supply voltage, forward voltage and current, with the next standard value and its power rating.
- RC and RL time constant calculatorTime constant τ = RC or L/R with the charge and discharge percentages at 1τ to 5τ, the value at any time and the −3 dB cut-off frequency.
- AWG to mm² wire gauge converterConvert American Wire Gauge to diameter, mm² and circular mils, or mm² and diameter to the matching AWG and the next IEC 60228 size, with copper resistance.