AC circuit formula tool
Impedance and Current Calculator
Convert between voltage, current, and impedance magnitude for AC circuit screening and worksheet notes.
Calculate Current from Impedance
Estimate current or voltage when an impedance magnitude is already known and the task is limited to V = I x Z.
Result
Amps
4 A
Result notes. Keep inputs, assumptions, and result together before using this value in project records.
Keep the entered values, assumptions, and result together when adding this calculation to job notes or submittal records. Final installation choices should align with the applicable code edition, equipment listing, manufacturer instructions, local amendments, and AHJ requirements.
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Power Quality
Open the power quality calculator to continue the workflow review.
Related charts
Impedance Reactance Chart
Use this impedance reactance chart for XL = 2 pi f L, XC = 1/(2 pi f C), 100 mH at 60 Hz = 37.7 ohms, and 100 uF = 26.5 ohms.
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Formula and field context
Convert between voltage, current, and impedance magnitude for AC circuit screening and worksheet notes.
Formula context
Impedance Reactance Chart
Use these formulas: XL = 2 pi f L and XC = 1/(2 pi f C) before combining reactance with resistance. At 60 Hz, 100 mH gives XL = 37.7 ohms and 100 uF gives XC = 26.5 ohms; Z = sqrt(R^2 + X^2) for a simple series model.
Formula
XL = 2 x pi x f x L. XC = 1 / (2 x pi x f x C). X = XL - XC. Z = sqrt(R^2 + X^2) for a simple series model.Variables to keep with the result
- XL is inductive reactance in ohms.
- XC is capacitive reactance in ohms.
- f is frequency in hertz.
- Z is impedance magnitude for the selected circuit model.
Formula and variables
For a basic impedance magnitude screen, current equals voltage divided by impedance, and voltage equals current multiplied by impedance. Use ohms for impedance, volts for voltage, and amps for current. This simplified worksheet uses magnitude only, not full complex impedance angle.
AC field context
Impedance is useful when resistance alone is not enough, such as coils, capacitors, filters, or measured AC circuit behavior. Keep frequency, component conditions, and whether the value is measured or calculated with the result.
Boundaries
This is not a load-flow study, short-circuit study, or power-quality diagnosis. Use the full impedance or power-quality calculators when resistance, reactance, angle, harmonics, or equipment interaction must be reviewed.