Capacitor Charge

Q = C × V

Quick answer

This calculator solves Q = C × V for Charge. With Capacitance 100 µF, Voltage 12 V, the result is 1.2 mC. It solves in 3 directions, so you can enter the values you have and get the one you need.

Calculator

Charge (µC)
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Formula

Q = C × V

Description

This is the defining equation of capacitance: the charge stored on a capacitor is directly proportional to the voltage applied across it. One farad is defined as one coulomb of charge per volt. In practice, most capacitors store microcoulombs or nanocoulombs of charge. The relationship is linear for ideal capacitors, meaning doubling the voltage doubles the stored charge. Current flowing into a capacitor is the rate of change of charge: I = dQ/dt = C × dV/dt, which is why capacitors block DC and pass AC.

Variables

  • Q — Charge in coulombs (C)
  • C — Capacitance in farads (F)
  • V — Voltage across the capacitor (V)

Practical Notes

One coulomb is an enormous amount of charge in electronics terms, equivalent to 6.24 × 10^18 electrons. A typical 100µF capacitor charged to 5V holds 500µC. The concept of charge conservation is central to Kirchhoff's Current Law and charge-based circuit analysis.

Symbols and units

Symbol Meaning Default unit Accepted units
Q Charge µC pC, nC, µC, mC, C
C Capacitance µF pF, nF, µF, mF, F
V Voltage V pV, nV, µV, mV, V, kV

Step by step

  1. 1. What you know: Capacitance 100 µF, Voltage 12 V
  2. 2. The relation: Q = C × V
  3. 3. Substitute: C = 100 µF, V = 12 V
  4. 4. Result: Charge = 1.2 mC

Worked examples

Minimum range

Given: Capacitance 100 nF, Voltage 0.33 V

Result: Charge = 33 nC

Low range

Given: Capacitance 1 µF, Voltage 3.3 V

Result: Charge = 3.3 µC

Typical

Given: Capacitance 100 µF, Voltage 12 V

Result: Charge = 1.2 mC

High range

Given: Capacitance 1 mF, Voltage 0.23 kV

Result: Charge = 0.23 C

Maximum range

Given: Capacitance 10 mF, Voltage 2.3 kV

Result: Charge = 23 C

Solving for each variable

Solve for Charge

Capacitance 100 nF, Voltage 0.33 V → 33 nC

Solve for Capacitance

Charge 100 nC, Voltage 0.33 V → 0.303 µF

Solve for Voltage

Charge 100 nC, Capacitance 100 nF → 1 V

How Charge changes with Capacitance

Capacitance (input) Charge (result)
10 µF 120 µC
25 µF 0.3 mC
50 µF 0.6 mC
75 µF 0.9 mC
100 µF 1.2 mC
150 µF 1.8 mC
0.2 mF 2.4 mC
0.4 mF 4.8 mC
0.7 mF 8.4 mC
1 mF 12 mC

The same result in other units

Unit Value
nC 1200000
µC 1200
mC 1.2
C 0.0012

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Frequently asked questions

How do you calculate Capacitor Charge?

Use Q = C × V. With Capacitance 100 µF, Voltage 12 V, Charge works out to 1.2 mC.

What is the formula for Capacitor Charge?

The formula is Q = C × V. This is the defining equation of capacitance: the charge stored on a capacitor is directly proportional to the voltage applied across it.

How do you find Capacitance when you know the other values?

Rearrange for Capacitance: with Charge 100 nC, Voltage 0.33 V, Capacitance is 0.303 µF.

How do you find Voltage when you know the other values?

Rearrange for Voltage: with Charge 100 nC, Capacitance 100 nF, Voltage is 1 V.

What units does Capacitor Charge use?

Charge is shown in nC, µC, mC, C. Values are held in SI base units internally, so you can mix prefixes without converting by hand.

Related Concepts

All Capacitors formulas →
Capacitive Reactance RC Time Constant Capacitor Energy Capacitor Charge Series Capacitance Parallel Capacitance Capacitor Impedance with ESR Capacitor Ripple Voltage

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