Capacitor formula tool
Capacitive Reactance Calculator
Calculate Xc from capacitance and frequency for capacitor, filter, and AC impedance worksheet notes.
Calculate Capacitive Reactance
Solve capacitive reactance from frequency and capacitance, or estimate capacitance from a target Xc.
Result notes
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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Related charts
Capacitor Reactance Chart
Use this capacitor reactance chart: 10 uF at 60 Hz is about 265 ohms; 120 V across it estimates 0.45 A before ESR and ratings.
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.
RC Time Constant Chart
Use this RC time constant chart: tau = R x C, 10 kOhm x 47 uF = 0.47 s, and 5 tau = 2.35 s for charge, discharge, or debounce checks.
Related guides
Impedance and Reactance Fundamentals for 60 Hz AC Circuits
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Formula and field context
Calculate Xc from capacitance and frequency for capacitor, filter, and AC impedance worksheet notes.
Formula context
Capacitor Reactance Chart
Capacitive reactance is XC = 1 / (2 pi f C). This component worksheet estimate shows that 10 uF at 60 Hz is about 265 ohms; with 120 V across the capacitor, ideal current is about 0.45 A. Use the chart before checking ESR, ripple current, ratings, and the wider system context.
Formula
XC = 1 / (2 x pi x f x C). Capacitor current estimate: I = V / XC.Variables to keep with the result
- XC is capacitive reactance in ohms.
- f is frequency in hertz.
- C is capacitance in farads.
- I is the AC current estimate when voltage across the capacitor is known.
Formula and variables
Capacitive reactance is Xc = 1 / (2 x pi x f x C). Frequency is in hertz and capacitance is converted to farads before calculation. Reactance decreases as frequency or capacitance increases.
Where it helps
This formula supports capacitor comparison, filter notes, bench checks, and AC impedance screening. At 60 Hz, the same capacitor has a very different reactance than it does in a high-frequency signal or switching circuit.
Component limits
Real capacitor behavior can differ because of tolerance, ESR, voltage rating, dielectric type, temperature, and frequency limits. Treat Xc as one part of the component review before using the full capacitor or impedance calculators.