Resonant Frequency Calculator

Before entering values

Keep distorted-waveform measurements separate from sine-wave assumptions. A source note beside each entry makes the result reproducible.

Values used below a division bar must stay positive. Convert units once, retain the original reading, and verify the converted magnitude. For the companion required capacitance calculation, open Motor Capacitor Calculator.

Inductance

Default example: 0.01 H. Enter inductance in H.

Capacitance

Default example: 10 µF. Enter capacitance in µF.

Common entry mistakes

Unit-prefix mistakes often dominate the arithmetic error.

Recheck decimal placement and unit conversion when the answer looks unusual.

Resonant frequency: calculation method

The displayed result follows f₀ = 1 ÷ (2π√LC). The entered quantities are Inductance and Capacitance.

For the example shown, resonant frequency equals 503.29 Hz. Treat that value as a demonstration, not a recommendation.

Find ideal LC resonance. A later impedance magnitude decision can draw on Parallel RLC Impedance Calculator.

What the number means

Interpret Resonant frequency on the same basis used for the source values. Compare it with impedance, phase, waveform, and equipment ratings.

A result without its source conditions is difficult to compare or audit.

Changing Inductance

Change Inductance from 0.01 H to 0.012 H and leave all other entries untouched. The displayed value changes from 503.29 Hz to 459.44 Hz.

Use a separate scenario when multiple conditions change together.

What the formula leaves out

Resistance lowers the quality factor and can shift practical response.

Outside the entered variables, consider harmonics, phase imbalance, saturation, and nonsinusoidal current. Test an additional scenario when an omitted effect has a plausible range.

Record frequency, waveform, phase arrangement, and whether voltage is line or phase.

Before carrying the answer forward

Review capacitance and the remaining entries as one case. If one value belongs to another temperature, load, or time period, separate the scenarios.

After calculating resonant frequency, compare its magnitude with a measured RMS case at the same frequency. An independent order-of-magnitude check can reveal a misplaced decimal or unit prefix.

If uncertainty remains, calculate labeled low and high cases. Include frequency-dependent loss, parasitics, and waveform distortion when those effects can change the decision.

Questions about Resonant Frequency