Capacitor Calculator — Charge, Voltage, Capacitance & EnergyQ = C·V · E = ½CV² · Farads · Coulombs · Joules · Volts
Use this free Capacitor Calculator to instantly compute any unknown capacitor electrical property — including electric charge (Q), voltage across the capacitor (V), capacitance (C), and stored electrical energy (E) — using the two fundamental capacitor formulas at the core of electrical engineering and electronics: Q = C × V (relating charge in Coulombs, capacitance in Farads, and voltage in Volts) and E = ½ × C × V² (calculating energy stored in a capacitor in Joules). Simply enter any two known capacitor values and this capacitor charge calculator will automatically solve all remaining electrical parameters in real time.
These capacitor equations are foundational to DC circuit analysis, AC circuit design, RC and LC filter circuits, power supply decoupling, energy storage systems, and signal processing applications across analog electronics, digital electronics, power electronics, and RF engineering. Whether you are designing a capacitor bank, calculating capacitor discharge time, sizing a smoothing capacitor for a power supply, or solving capacitor problems in physics and electrical engineering coursework — this online capacitor calculator covers electrolytic, ceramic, film, and supercapacitor types across all standard capacitance units: F · mF · μF · nF · pF.
⚠ Engineering Disclaimer: This capacitor calculator is intended for educational, academic, and reference purposes only. Results are based on ideal capacitor models and do not account for real-world factors including equivalent series resistance (ESR), dielectric leakage, temperature coefficient, or voltage rating tolerances. Always verify all values independently and consult a licensed electrical engineer before applying results to safety-critical, industrial, or high-voltage applications.
Enter any two known electrical values — charge (Q) in Coulombs, voltage (V) in Volts, capacitance (C) in Farads, or stored energy (E) in Joules — and this capacitor energy calculator will instantly and automatically solve all remaining capacitor parameters using the capacitance formula Q = CV and capacitor energy formula E = ½CV², giving you a complete picture of your capacitor circuit's electrical behavior in a single calculation.
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Capacitor Calculator — Charge, Energy, Time Constants, and Series/Parallel Combinations
Capacitors store energy in an electric field, characterized by capacitance C in Farads. A 100µF capacitor charged to 12V stores Q = CV = 0.0012 coulombs of charge and E = ½CV² = 0.0072 joules of energy — enough to power a small LED for a fraction of a second. In camera flash circuits, capacitors at 300V store substantial energy for rapid discharge. In power supply filtering, capacitors smooth voltage ripple by supplying current during brief supply drops. The calculator computes charge, energy, and voltage for any capacitance and voltage combination.
The RC time constant τ = RC determines how quickly a capacitor charges through a series resistance. After one time constant, a capacitor charges to 63.2% of the supply voltage; after five time constants, it is 99.3% charged. A 10kΩ resistor with a 100µF capacitor gives τ = 1 second. This timing relationship governs debouncing circuits, timing delays, filter corner frequencies, and analog integrators. The calculator converts between R, C, and τ with the percentage-charged calculation for any elapsed time.
Capacitors in series reduce total capacitance (inverse addition, like parallel resistors); capacitors in parallel increase total capacitance (direct addition, like series resistors). Two 100µF capacitors in series give 50µF; in parallel they give 200µF. Series connections increase the voltage rating of the combination — two 50V capacitors in series can handle 100V. Parallel connections increase capacitance at the same voltage. The calculator handles series, parallel, and mixed capacitor networks with combined capacitance and effective voltage rating.