What is the relationship between charge, capacitance, and voltage?

Q = C*V. A 100 uF capacitor charged to 12 V stores Q = 100e-6 * 12 = 1.2 x 10^-3 C = 1.2 mC. Increasing either capacitance or voltage proportionally increases stored charge.

How is this used in camera flash circuits?

A large capacitor (e.g., 1000 uF) is charged to a high voltage (e.g., 300 V), storing Q = 0.3 C. When discharged rapidly through a xenon tube, it delivers a brief but intense flash of light.

What is the difference between charge and energy in a capacitor?

Charge Q = C*V measures the number of coulombs of electrons displaced. Energy E = (1/2)*C*V^2 measures the work stored in the electric field. Doubling voltage doubles Q but quadruples E.

Capacitor Charge Calculator

Calculate the electric charge stored on a capacitor using Q = CV. Enter capacitance in farads and voltage in volts to find the stored charge in coulombs for any capacitor circuit.

By AbraCalc Editorial Team · Reviewed by AbraCalc Methodology Review · Last reviewed: 2026-06-25

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How to use this tool

Enter capacitance (c) and voltage (v) in the fields above.
Results update instantly as you type — or click Calculate.
Read your charge (q) and the full breakdown beneath it.

Formula

Q = C × V

How it works

Multiply capacitance (F) by voltage (V) to obtain stored charge in coulombs.

Worked example

Common mistakes to avoid

Entering capacitance in microfarads (uF) without converting — 1 uF = 10^-6 F; using the uF value directly overstates charge by a factor of one million.
Confusing charge Q (coulombs) with energy stored E = (1/2)*C*V^2 (joules) — Q = CV gives charge, not energy.
Using peak voltage for AC circuits — Q = CV strictly applies for DC (static) charge; for AC the charge oscillates and the formula must be applied instantaneously.

Key terms

Frequently asked questions

What is the relationship between charge, capacitance, and voltage?: Q = C*V. A 100 uF capacitor charged to 12 V stores Q = 100e-6 * 12 = 1.2 x 10^-3 C = 1.2 mC. Increasing either capacitance or voltage proportionally increases stored charge.
How is this used in camera flash circuits?: A large capacitor (e.g., 1000 uF) is charged to a high voltage (e.g., 300 V), storing Q = 0.3 C. When discharged rapidly through a xenon tube, it delivers a brief but intense flash of light.
What is the difference between charge and energy in a capacitor?: Charge Q = C*V measures the number of coulombs of electrons displaced. Energy E = (1/2)*C*V^2 measures the work stored in the electric field. Doubling voltage doubles Q but quadruples E.