Convert Hz to amps for an inductor or capacitor from voltage and inductance or capacitance, or find series RLC current; frequency alone cannot give amps.
| Hz to Amps | Amps to Hz |
|---|---|
| 50 Hz = 38.197 A | 0.1 A = 19099 Hz |
| 60 Hz = 31.831 A | 0.2 A = 9549 Hz |
| 100 Hz = 19.099 A | 0.5 A = 3820 Hz |
| 120 Hz = 15.916 A | 1 A = 1910 Hz |
| 400 Hz = 4.775 A | 2 A = 955 Hz |
| 500 Hz = 3.820 A | 5 A = 382 Hz |
| 1000 Hz = 1.910 A | 10 A = 191 Hz |
| 2000 Hz = 0.955 A | 20 A = 95.5 Hz |
| 5000 Hz = 0.382 A | 30 A = 63.7 Hz |
| 10000 Hz = 0.191 A | 40 A = 47.7 Hz |
| Formula (inductor): I = V ÷ (2π f L). Assumes RMS, V = 120 V, L = 10 mH. | |
| Hz to Amps | Amps to Hz |
|---|---|
| 50 Hz = 0.377 A | 0.1 A = 13.3 Hz |
| 60 Hz = 0.452 A | 0.2 A = 26.5 Hz |
| 100 Hz = 0.754 A | 0.5 A = 66.3 Hz |
| 120 Hz = 0.905 A | 1 A = 133 Hz |
| 400 Hz = 3.016 A | 2 A = 265 Hz |
| 500 Hz = 3.770 A | 5 A = 663 Hz |
| 1000 Hz = 7.540 A | 10 A = 1326 Hz |
| 2000 Hz = 15.080 A | 15 A = 1989 Hz |
| 5000 Hz = 37.699 A | 20 A = 2653 Hz |
| 10000 Hz = 75.398 A | 30 A = 3979 Hz |
| Formula (capacitor): I = 2π f C V. Assumes RMS, V = 120 V, C = 10 µF. | |
| Hz to Amps | Amps to Hz |
|---|---|
| 50 Hz = 76.394 A | 1 A = 3820 Hz |
| 60 Hz = 63.662 A | 2 A = 1910 Hz |
| 100 Hz = 38.197 A | 5 A = 763.9 Hz |
| 400 Hz = 9.549 A | 10 A = 382 Hz |
| 1000 Hz = 3.820 A | 20 A = 191 Hz |
| Formula (inductor): I = V ÷ (2π f L). Assumes RMS, V = 240 V, L = 10 mH. | |
Hz To Amps Formulas
Frequency alone cannot convert to current. These formulas apply to ideal linear components in sinusoidal steady state, using RMS voltage and current and positive frequency. The calculator retains current, frequency, voltage and component solves for a pure inductor or capacitor, plus current for a series RLC circuit. It does not predict motor starting, saturation, equipment compatibility or safe wiring.
Inductor: I = V / (2 * pi * f * L)
Capacitor: I = 2 * pi * f * C * V
Series RLC circuit: I = V / Z, where Z = sqrt(R^2 + (X_L - X_C)^2)
In series mode, blank resistance or inductance means zero; blank capacitance means the capacitor is absent and bypassed. This does not represent a zero-farad capacitor or a physical open circuit. Enter positive capacitance when present. Display precision defaults to four significant figures, with three to six selectable. Zero voltage is supported for forward current, while frequency and component inverses require positive known values to avoid nonunique or zero-frequency cases.
Variables:
- I = current in amperes (A, RMS)
- V = voltage (V, RMS)
- f = frequency in hertz (Hz)
- L = inductance in henries (H)
- C = capacitance in farads (F)
- R = resistance in ohms
- X_L = inductive reactance = 2 * pi * f * L
- X_C = capacitive reactance = 1 / (2 * pi * f * C)
For a pure inductor with no resistance, current drops as frequency rises because inductive reactance (X_L) increases linearly with frequency. The opposite is true for capacitors: capacitive reactance (X_C) falls as frequency rises, so current increases.
How Frequency and Current Interact in AC Circuits
Hz and amps measure fundamentally different things. Hertz counts the number of complete voltage/current cycles per second. Amperes measure the rate of charge flow. There is no fixed ratio between them. The relationship depends entirely on the impedance of the circuit, which changes with the components present.
In a purely resistive circuit (a heater, an incandescent bulb), changing the frequency from 50 Hz to 60 Hz has zero effect on current. Resistance does not depend on frequency. In a circuit with inductors or capacitors, though, impedance is frequency-dependent, so the same voltage at a different frequency produces a different current.
Inductive Loads
For an ideal constant inductance, X_L = 2 * pi * f * L. Doubling frequency doubles reactance and halves current at fixed voltage. For example, an ideal 100 mH inductor has X_L about 31.4 ohms at 50 Hz and 37.7 ohms at 60 Hz. Motors, transformers and solenoids also involve resistance, back EMF, loading and possible saturation; the simple inductor model does not determine their actual current or supply compatibility.
Capacitive Loads
Power-factor correction capacitor banks, filter capacitors, and coupling capacitors are capacitive. Their reactance is X_C = 1 / (2 * pi * f * C). As frequency rises, X_C drops and current rises. A 10 uF capacitor at 120 V draws about 0.452 A at 60 Hz but 0.377 A at 50 Hz.
50 Hz vs 60 Hz Power Grids
Most of the world uses one of two standard AC frequencies. North America, parts of South America, South Korea, Saudi Arabia, and the Philippines use 60 Hz. Europe, most of Africa, Asia, and Australia use 50 Hz. Japan is split: eastern Japan (Tokyo, Yokohama) runs 50 Hz while western Japan (Osaka, Nagoya) runs 60 Hz, a legacy of importing different generators in the 1890s.
For purely resistive loads, the grid frequency does not matter. For reactive loads, the 20% frequency difference between 50 Hz and 60 Hz causes meaningful changes in current draw. Operating a 60 Hz transformer at 50 Hz at the same voltage raises the volts-per-hertz ratio and may cause saturation and excess magnetizing current; consult its actual rating rather than treating this calculator as a compatibility check. Variable frequency drives (VFDs) exploit this relationship deliberately, controlling motor speed by adjusting the output frequency and voltage together.
Common Component Values and Their Currents
The values below are illustrative context, not manufacturer specifications or design ratings. Real-device current cannot generally be inferred from a single L or C value. Verify component data and actual operating conditions; audio signal voltages in particular are not assumed to be 120 V RMS.
- Small AC motor (washing machine): winding inductance around 50 to 200 mH, drawing roughly 1 to 6 A depending on load and resistance.
- Fluorescent lamp ballast: inductance around 0.5 to 2 H, limiting current to 0.3 to 0.5 A at line frequency.
- Power-factor correction capacitor (residential): 5 to 25 uF, drawing 0.2 to 1.1 A of reactive current at 60 Hz / 120 V.
- AC coupling capacitor (audio amplifier): 1 to 10 uF, passes milliamp-level signal currents at audio frequencies (20 Hz to 20 kHz).
- Transformer primary (small appliance): inductance 1 to 10 H, magnetizing current well under 1 A at 60 Hz.
Worked Example
A 10 mH inductor is connected to a 120 V RMS, 60 Hz supply. Find the RMS current.
Step 1: Calculate inductive reactance. X_L = 2 * pi * 60 * 0.010 = 3.7699 ohms.
Step 2: Calculate current. I = 120 / 3.7699 = 31.831 A.
This matches the 60 Hz row in the inductor table above. In practice, real inductors have winding and AC loss resistance, parasitic capacitance and current limits. Enter actual loss resistance in the series mode for that simplified model; no universal winding-resistance range is assumed.
Skin Effect at High Frequencies
Skin effect changes conductor AC resistance according to frequency, material and geometry. It has no single frequency or diameter threshold that applies to every circuit. The ideal reactance model does not include skin effect, proximity effect or parasitics; use frequency-dependent component data when these matter.
Resonance
When an inductor and capacitor are in series, there is one specific frequency where X_L exactly equals X_C. At this resonant frequency, the two reactances cancel and the impedance drops to just the resistance R. For positive resistance R, the ideal series current reaches V/R, which can greatly exceed off-resonance current. With zero loss resistance the ideal resonant model is singular and has no finite steady-state current; the calculator flags this condition instead of returning a huge rounding artifact. The resonant frequency is f_r = 1 / (2 * pi * sqrt(L * C)). Series LC resonance is used in radio tuning circuits, bandpass filters, and can also cause dangerous overcurrents in power systems if a capacitor bank resonates with transformer inductance at a harmonic frequency.
