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Capacitance Calculator

Find capacitance from stored charge and voltage with C = Q / V — or solve for charge or voltage. Also shows the energy stored in the capacitor.

 

Formula

$$ C = \frac{Q}{V} \qquad Q = C\,V \qquad V = \frac{Q}{C} \qquad E = \tfrac12 C V^2 $$

Worked example

A capacitor holding 0.0001 C at 10 V has \( C = Q/V = 0.0001/10 = 10^{-5}\ \text{F} = 10\ \mu\text{F} \), storing \( \tfrac12 C V^2 = 0.5\ \text{mJ} \) of energy.

How it works

Capacitance measures how much charge a component stores per volt: C = Q/V. A one-farad capacitor holds one coulomb per volt — a very large value, so real capacitors are usually rated in microfarads (µF) or picofarads (pF).

Enter any two of capacitance, charge and voltage to find the third. The energy stored is E = ½CV², which is what lets capacitors deliver quick bursts of power in flashes, power supplies and circuits.

Frequently asked questions

What is the formula for capacitance?

C = Q/V — the charge stored divided by the voltage across the capacitor. The unit is the farad (F).

What are the units of capacitance?

The farad (F), equal to one coulomb per volt. Practical capacitors are usually in microfarads (1 µF = 10⁻⁶ F) or picofarads (1 pF = 10⁻¹² F).

How much energy is stored in a capacitor?

E = ½CV² — half the capacitance times the voltage squared. This calculator reports it alongside the result.

How do you find the charge on a capacitor?

Multiply capacitance by voltage: Q = CV. Set 'Solve for' to Charge and enter C and V.

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