Quality Factor (Q) Calculator

This quality factor calculator works out the Q factor, resonant frequency and bandwidth of a series RLC circuit, so you can see how sharp and selective the tuned response will be. You enter three values: the resistance R in ohms, the inductance L in henries and the capacitance C in farads. From these the calculator returns the quality factor Q, the resonant frequency in hertz, and the bandwidth, which is the resonant frequency divided by Q. Q describes how much energy the circuit stores compared with how much it loses each cycle: a high Q gives a narrow, tall resonance peak and a selective, low-loss response, while a low Q gives a broad, heavily damped one. It depends on the ratio of reactance to resistance, so lowering the resistance or increasing the inductance-to-capacitance ratio raises Q. This is useful for anyone designing or checking tuned circuits, oscillators and filters, including electronics students, hobbyists and engineers who need a quick check of resonant behaviour before building or simulating a circuit. Enter your own R, L and C values, or try the worked example of 10 ohms, 1 millihenry and 0.1 microfarad, which gives a resonant frequency of about 15.9 kHz and a Q of 10. The calculator assumes ideal components and rounds results for display, so treat the figures as a close estimate rather than an exact lab measurement.

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