Series AC Impedance Calculator
Calculate impedance, RMS current, phase, power factor and power for a resistor with optional series inductance and capacitance.
YOUR CALCULATION
Result
—
Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Calculate inductive and capacitive reactance at the source frequency. Combine the real resistance and net imaginary reactance as a complex magnitude. Divide RMS voltage by impedance and use the phase angle for power.
Z=√(R²+(2πfL−1/(2πfC))²); I=Vrms/Z; P=I²R
Worked example
For a 40 Ω resistor alone at 120 V RMS, impedance is 40 Ω, current is 3 A and real power is 360 W. Inductive and capacitive reactances can cancel at resonance.
Assumptions and input details
Linear lumped components in sinusoidal steady state, all in series. Resistance must be positive (1e−9–1e12 Ω); ideal zero-resistance resonance is unsupported. Frequency is positive up to 1e12 Hz; present L/C are positive 1e−15–1e9 H/F. Source voltage is nonnegative RMS, not peak. Positive phase/reactive power is inductive (current lags); negative is capacitive. S is apparent power in VA, Q reactive power in var, P real power in W. Component voltages add as phasors. Parasitics and frequency-dependent component ratings are not inferred.
References: OpenStax RLC series circuits
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
SI prefixes are explicit: for example, milli means one thousandth, micro one millionth and kilo one thousand. Changing a unit changes the interpretation of the entered number.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
Enter two electrical quantities to find voltage, current, resistance and power for an ideal DC resistor. Follow the equations and current–voltage graph.
Calculate the equivalent capacitance of 2–20 capacitors in series or parallel. Enter supply voltage for ideal charge, per-capacitor voltage and stored energy.
Calculate the ideal AC voltage ratio and a simplified efficiency-based current and power balance. Keep ideal voltage scaling separate from entered losses.
Reserved advertising space.