Resonant Frequency Calculator

Pick a model and enter precise parameters today. Get frequency, omega, and quality estimates instantly. Designed for students, makers, and test bench work everywhere.

Calculator

Choose the physical system you want to model.
R is used for Q and bandwidth estimates.
You can specify diameter or cross-sectional area.
Uses c ≈ 331.3 + 0.606·T.
Typical coax is ~0.66, foam ~0.8–0.9.

Example Data

Model Example inputs Expected resonant frequency
LC (ideal) L = 10 mH, C = 100 nF ≈ 159.15 Hz
Series RLC L = 1 mH, C = 10 nF, R = 2 Ω ≈ 50.33 kHz (ideal), slightly lower damped
Mass–spring k = 1200 N/m, m = 0.8 kg ≈ 6.16 Hz
Helmholtz V = 1.5 L, L = 3 cm, d = 2.5 cm, T = 20°C ≈ 140–170 Hz (depends on end correction)
Standing-wave Quarter-wave, L = 0.5 m, VF = 0.66 ≈ 98.93 MHz

Formula Used

How to Use This Calculator

  1. Select a model that matches your system: LC/RLC, mass–spring, Helmholtz, or standing-wave.
  2. Enter your parameters and choose units from each dropdown.
  3. Press Calculate to see results directly below the header.
  4. Review supporting outputs like angular frequency, period, Q, and bandwidth.
  5. Use Download CSV or Download PDF for a shareable report.

Article

Understanding resonance

Resonance happens when a system naturally oscillates with maximum response at a specific frequency. At that point, energy transfers efficiently between storage elements, like inductors and capacitors, or mass and springs. Knowing the resonant frequency helps you predict vibration peaks, filter behavior, and stability margins across many engineering domains.

LC resonance in circuits

For an ideal LC tank, the resonant frequency depends only on inductance L and capacitance C. Small changes in either component shift the peak noticeably, especially at higher frequencies. This calculator converts common units and reports both frequency and angular frequency for quick design checks.

Including resistance and damping

Real circuits include losses, modeled by resistance. In a series RLC, damping lowers the ringing and can slightly reduce the oscillation frequency compared with the ideal value. The calculator estimates the damped frequency when applicable and flags overdamped cases where sustained oscillation cannot form. Even modest ESR in capacitors can dominate at kHz to MHz ranges, so always verify datasheets carefully.

Quality factor and bandwidth

Quality factor Q describes how sharp the resonance peak is. Higher Q means narrower bandwidth and greater selectivity but slower settling. The calculator provides practical Q and an approximate bandwidth Δf so you can compare component choices, evaluate filtering targets, and anticipate sensitivity to tolerances and temperature drift.

Mechanical resonance with springs

A mass–spring system resonates when spring stiffness k and mass m exchange kinetic and potential energy. The model assumes small oscillations and negligible damping, which is common for first-pass sizing. Use it for shaker tests, isolation mounts, and estimating natural frequencies in prototypes.

Helmholtz resonance in cavities

Helmholtz resonance describes air oscillation in a cavity with a neck, like bottles, enclosures, and vents. The result depends on cavity volume, neck area, and effective neck length. The calculator includes a simple end correction so predictions better match practical geometries in workshops.

Standing-wave resonance in lines

Transmission lines and antennas resonate when their length matches a fraction of the wavelength. Quarter-wave and half-wave modes are common, and the velocity factor adjusts for dielectric materials. Use the length or frequency mode to size elements and quickly sanity-check RF builds.

FAQs

1) Which model should I choose?

Use LC/RLC for electronic tanks, spring for vibration systems, Helmholtz for cavities with a neck, and standing-wave for lines or antennas. Pick the model that matches your energy storage elements.

2) Why is series RLC damped frequency lower than ideal?

Resistance adds damping. In a series RLC, the damped frequency is ωd = √(ω0² − (R/2L)²). If damping is strong, the system becomes overdamped and no oscillatory resonance occurs.

3) Do I need to convert units before entering values?

No. Choose units beside each input. The calculator converts to SI internally, then reports results in Hz and rad/s. For wave mode, frequency units can be Hz to GHz.

4) How accurate is the Helmholtz result?

It is a good estimate for simple cavities and short necks. Real results depend on neck flares, wall thickness, leaks, and damping. Use it for sizing, then validate by measurement or simulation when precision matters.

5) What velocity factor should I use for standing-wave mode?

Use the cable or dielectric velocity factor from the datasheet. Typical solid PE coax is around 0.66, foam is often 0.8–0.9, and air-spaced structures can approach 1.0.

6) Why does measured resonance shift from calculated?

Component tolerances, temperature, stray capacitance/inductance, mounting geometry, and loss all shift resonance. For high-Q designs, small parasitics can move the peak significantly. Measure with a sweep and update inputs to match.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.