RLC Circuit Calculator
Step and sinusoidal response of series RLC circuits: natural frequency, damping ratio, Q factor, and bandwidth
This free online rlc circuit calculator provides instant results with no signup required. All calculations run directly in your browser — your data is never sent to a server. Supports both metric (SI) and imperial units with built-in unit selection dropdowns on every input field, so you can work in whatever units your problem provides. Designed for engineering students and professionals working through coursework, design projects, or quick reference calculations.
RLC Circuit Calculator
Step or sinusoidal response, natural frequency, damping, and quality factor for series RLC.
Natural Freq. ωn
447.21 rad/s
Resonant Freq. f₀
71.18 Hz
Damping Ratio ζ
0.2236
Classification
Underdamped
Quality Factor Q
2.236
Bandwidth BW
31.83 Hz
Time Constant τ
10.00 ms
Step Response v_C(t)
Transient Response Data Table
| t (ms) | v_C (V) |
|---|---|
| 0.000 | 0.000000 |
| 0.500 | 0.024090 |
| 1.000 | 0.092120 |
| 1.500 | 0.196700 |
| 2.000 | 0.329400 |
| 2.500 | 0.481240 |
| 3.000 | 0.643210 |
| 3.500 | 0.806670 |
| 4.000 | 0.963740 |
| 4.500 | 1.107580 |
| 5.000 | 1.232630 |
| 5.500 | 1.334760 |
| 6.000 | 1.411310 |
| 6.500 | 1.461090 |
| 7.000 | 1.484280 |
| 7.500 | 1.482320 |
| 8.000 | 1.457690 |
| 8.500 | 1.413710 |
| 9.000 | 1.354320 |
| 9.500 | 1.283790 |
| 10.000 | 1.206530 |
| 10.500 | 1.126830 |
| 11.000 | 1.048710 |
| 11.500 | 0.975710 |
| 12.000 | 0.910810 |
| 12.500 | 0.856320 |
| 13.000 | 0.813810 |
| 13.500 | 0.784180 |
| 14.000 | 0.767590 |
| 14.500 | 0.763590 |
| 15.000 | 0.771170 |
| 15.500 | 0.788880 |
| 16.000 | 0.814900 |
| 16.500 | 0.847220 |
| 17.000 | 0.883700 |
| 17.500 | 0.922220 |
| 18.000 | 0.960760 |
| 18.500 | 0.997490 |
| 19.000 | 1.030850 |
| 19.500 | 1.059570 |
| 20.000 | 1.082730 |
| 20.500 | 1.099770 |
| 21.000 | 1.110460 |
| 21.500 | 1.114900 |
| 22.000 | 1.113470 |
| 22.500 | 1.106800 |
| 23.000 | 1.095710 |
| 23.500 | 1.081130 |
| 24.000 | 1.064100 |
| 24.500 | 1.045650 |
| 25.000 | 1.026800 |
| 25.500 | 1.008470 |
| 26.000 | 0.991480 |
| 26.500 | 0.976510 |
| 27.000 | 0.964080 |
| 27.500 | 0.954540 |
| 28.000 | 0.948050 |
| 28.500 | 0.944650 |
| 29.000 | 0.944190 |
| 29.500 | 0.946420 |
| 30.000 | 0.950980 |
| 30.500 | 0.957420 |
| 31.000 | 0.965270 |
| 31.500 | 0.974020 |
| 32.000 | 0.983170 |
| 32.500 | 0.992240 |
| 33.000 | 1.000820 |
| 33.500 | 1.008540 |
| 34.000 | 1.015130 |
| 34.500 | 1.020370 |
| 35.000 | 1.024140 |
| 35.500 | 1.026420 |
| 36.000 | 1.027220 |
| 36.500 | 1.026660 |
| 37.000 | 1.024890 |
| 37.500 | 1.022110 |
| 38.000 | 1.018540 |
| 38.500 | 1.014440 |
| 39.000 | 1.010040 |
| 39.500 | 1.005580 |
| 40.000 | 1.001290 |
| 40.500 | 0.997340 |
| 41.000 | 0.993900 |
| 41.500 | 0.991070 |
| 42.000 | 0.988930 |
| 42.500 | 0.987520 |
| 43.000 | 0.986840 |
| 43.500 | 0.986840 |
| 44.000 | 0.987470 |
| 44.500 | 0.988630 |
| 45.000 | 0.990220 |
| 45.500 | 0.992130 |
| 46.000 | 0.994220 |
| 46.500 | 0.996390 |
| 47.000 | 0.998520 |
| 47.500 | 1.000520 |
| 48.000 | 1.002310 |
| 48.500 | 1.003810 |
| 49.000 | 1.005000 |
| 49.500 | 1.005830 |
| 50.000 | 1.006310 |
| 50.500 | 1.006440 |
| 51.000 | 1.006250 |
| 51.500 | 1.005790 |
| 52.000 | 1.005100 |
| 52.500 | 1.004230 |
| 53.000 | 1.003240 |
| 53.500 | 1.002190 |
| 54.000 | 1.001140 |
| 54.500 | 1.000140 |
| 55.000 | 0.999220 |
| 55.500 | 0.998430 |
| 56.000 | 0.997790 |
| 56.500 | 0.997310 |
| 57.000 | 0.997010 |
| 57.500 | 0.996880 |
| 58.000 | 0.996900 |
| 58.500 | 0.997070 |
| 59.000 | 0.997370 |
| 59.500 | 0.997760 |
| 60.000 | 0.998220 |
| 60.500 | 0.998720 |
| 61.000 | 0.999230 |
| 61.500 | 0.999730 |
| 62.000 | 1.000200 |
| 62.500 | 1.000610 |
| 63.000 | 1.000960 |
| 63.500 | 1.001220 |
| 64.000 | 1.001400 |
| 64.500 | 1.001500 |
| 65.000 | 1.001520 |
| 65.500 | 1.001470 |
| 66.000 | 1.001350 |
| 66.500 | 1.001170 |
| 67.000 | 1.000960 |
| 67.500 | 1.000730 |
| 68.000 | 1.000480 |
| 68.500 | 1.000230 |
| 69.000 | 0.999990 |
| 69.500 | 0.999780 |
| 70.000 | 0.999600 |
| 70.500 | 0.999450 |
| 71.000 | 0.999350 |
| 71.500 | 0.999280 |
| 72.000 | 0.999260 |
| 72.500 | 0.999270 |
| 73.000 | 0.999320 |
| 73.500 | 0.999390 |
| 74.000 | 0.999490 |
| 74.500 | 0.999600 |
| 75.000 | 0.999720 |
| 75.500 | 0.999840 |
| 76.000 | 0.999960 |
| 76.500 | 1.000060 |
| 77.000 | 1.000160 |
| 77.500 | 1.000240 |
| 78.000 | 1.000300 |
| 78.500 | 1.000340 |
| 79.000 | 1.000360 |
| 79.500 | 1.000360 |
| 80.000 | 1.000340 |
| 80.500 | 1.000310 |
| 81.000 | 1.000270 |
| 81.500 | 1.000220 |
| 82.000 | 1.000160 |
| 82.500 | 1.000100 |
| 83.000 | 1.000040 |
| 83.500 | 0.999990 |
| 84.000 | 0.999940 |
| 84.500 | 0.999900 |
| 85.000 | 0.999870 |
| 85.500 | 0.999840 |
| 86.000 | 0.999830 |
| 86.500 | 0.999820 |
| 87.000 | 0.999830 |
| 87.500 | 0.999840 |
| 88.000 | 0.999860 |
| 88.500 | 0.999880 |
| 89.000 | 0.999910 |
| 89.500 | 0.999940 |
| 90.000 | 0.999970 |
| 90.500 | 0.999990 |
| 91.000 | 1.000020 |
| 91.500 | 1.000040 |
| 92.000 | 1.000060 |
| 92.500 | 1.000070 |
| 93.000 | 1.000080 |
| 93.500 | 1.000080 |
| 94.000 | 1.000080 |
| 94.500 | 1.000080 |
| 95.000 | 1.000070 |
| 95.500 | 1.000060 |
| 96.000 | 1.000050 |
| 96.500 | 1.000040 |
| 97.000 | 1.000020 |
| 97.500 | 1.000010 |
| 98.000 | 1.000000 |
| 98.500 | 0.999980 |
| 99.000 | 0.999970 |
| 99.500 | 0.999970 |
| 100.000 | 0.999960 |
Formulas
How to Use This Calculator
Enter your input values
Fill in all required input fields for the RLC Circuit Calculator. Most fields include unit selectors so you can work in your preferred unit system — metric or imperial, whichever matches your problem.
Review your inputs
Double-check that all values are correct and that you have selected the right units for each field. Incorrect units are the most common source of calculation errors and can produce results that are off by factors of 2, 10, or more.
Read the results
The RLC Circuit Calculator instantly computes the output and displays results with units clearly labeled. All calculations happen in your browser — no loading time and no data sent to a server.
Explore parameter sensitivity
Try adjusting individual input values to see how the output changes. This is a quick and effective way to develop intuition about how different parameters influence the result and to identify which inputs have the largest effect.
Formula Reference
RLC Circuit Calculator Formula
See calculator inputs for the governing equation
Variables: All variables and their units are labeled in the calculator interface above. Input fields accept values in multiple unit systems — select your preferred unit from the dropdown next to each field.
When to Use This Calculator
- •Use the RLC Circuit Calculator when solving homework or exam problems that require quick numerical verification of your hand calculations — instant feedback helps identify arithmetic errors before they propagate.
- •Use it during the early design phase to rapidly iterate on parameters and narrow down feasible configurations before committing time to detailed finite element simulations or full design packages.
- •Use it when reviewing a colleague's calculation or checking a vendor's data sheet for plausibility — a quick sanity check can prevent costly downstream errors.
- •Use it to generate reference data for a technical report or presentation without manual computation, ensuring consistent, reproducible numbers throughout the document.
- •Use it in the field when a quick estimate is needed and a full engineering software package is not available.
About This Calculator
The RLC Circuit Calculator is a precision engineering calculation tool designed for students, engineers, and technical professionals. Step and sinusoidal response of series RLC circuits: natural frequency, damping ratio, Q factor, and bandwidth All calculations are performed using established engineering formulas from the relevant scientific literature and standards. Inputs support both metric (SI) and imperial unit systems, with unit conversion handled automatically — simply select your preferred unit from the dropdown next to each field. Results are computed instantly in the browser without sending data to a server, ensuring both speed and privacy. This calculator is intended as a supplementary tool for learning and design exploration; always verify results against authoritative references for safety-critical applications.
The Theory Behind It
A series RLC circuit contains a resistor, inductor, and capacitor in series, driven by a voltage source. Its natural behavior is determined by the damping ratio ζ and natural frequency ω_n, analogous to a mechanical spring-mass-damper system. Natural frequency ω_n = 1/√(LC). Damping factor α = R/(2L). Damping ratio ζ = α/ω_n = (R/2)·√(C/L). Three damping regimes: underdamped (ζ < 1, oscillatory response, most common), critically damped (ζ = 1, fastest non-oscillatory response), overdamped (ζ > 1, slow non-oscillatory return). For underdamped series RLC, the damped oscillation frequency is ω_d = ω_n·√(1−ζ²). Step response: oscillatory ring-down about final value for underdamped; exponential approach for critical and overdamped. Sinusoidal (steady-state) response: peak amplitude at resonance (ω = ω_n) for underdamped, lower and broader peak for higher damping. RLC circuits are the electrical equivalent of mechanical vibration systems, and the same math applies to both. They are used in signal filters, oscillators, antenna matching networks, and power conditioning. The calculator analyzes both transient (step) and steady-state (sinusoidal) response of series RLC circuits.
Real-World Applications
- •Tuned radio receivers: RLC tank circuits select specific radio frequencies from the broad spectrum picked up by the antenna.
- •Band-pass and band-stop filters: allow or block specific frequency ranges in audio and communication circuits.
- •Voltage regulator smoothing: RLC filtering reduces ripple in DC power supplies after rectification.
- •Crystal radio design: classical wireless radio uses a simple LC tank for tuning without amplification.
- •Transient voltage suppression: RLC circuits absorb voltage spikes and protect sensitive electronics.
Frequently Asked Questions
What is an RLC circuit?
An electrical circuit containing resistance R, inductance L, and capacitance C. These three elements represent dissipation, magnetic energy storage, and electric energy storage respectively. Series and parallel RLC circuits have different response characteristics but are both governed by the same ω_n, ζ, and damping regime concepts as mechanical oscillators.
What's the resonant frequency of an RLC circuit?
ω_r = 1/√(LC), or f_r = 1/(2π√(LC)) in Hz. At this frequency, inductive and capacitive reactances cancel, leaving only resistance. For L = 10 mH and C = 10 μF: f_r = 1/(2π·√(0.01·0.00001)) = 1/(2π·0.0003162) ≈ 503 Hz. At resonance, the circuit has minimum impedance (series) or maximum impedance (parallel).
What's Q for an RLC circuit?
For series RLC: Q = (1/R)·√(L/C) = ω_r·L/R. For parallel RLC: Q = R·√(C/L) = R/(ω_r·L). Q is the ratio of stored to dissipated energy per cycle, measuring how sharply tuned the circuit is. High Q (> 10) gives sharp frequency selectivity; low Q (< 1) gives broad response. Q also relates to the damping ratio: ζ = 1/(2Q).
When does an RLC circuit oscillate?
When underdamped (ζ < 1, equivalent to Q > 0.5). The natural frequency of oscillation is ω_d = ω_n·√(1−ζ²), slightly lower than ω_n. Overdamped circuits (ζ > 1) return to equilibrium without oscillation. Critically damped (ζ = 1) is the fastest non-oscillating response. Most filter designs are underdamped to provide frequency selectivity.
What's the step response of an underdamped RLC?
Oscillating decay about the steady-state value: v(t) = V_ss·(1 − e^(−αt)·(cos(ω_d·t) + (α/ω_d)·sin(ω_d·t))), where V_ss is the final voltage, α = R/(2L), and ω_d = √(ω_n² − α²). The oscillation period is 2π/ω_d, and the amplitude decays exponentially with time constant 1/α. Higher R (or lower L) means faster decay and less ringing.
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