Capacitance Charge Calculator
Calculate charge, capacitance, or voltage using Q = C × V. Select the calculation mode below.
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What is Capacitor Charge?
Capacitor charge is the amount of electric charge stored in a capacitor when voltage is applied. The relationship between charge, capacitance, and voltage is linear:
Q = C × V
Where Q is charge in coulombs (C), C is capacitance in farads (F), and V is voltage in volts (V). This fundamental relationship governs how capacitors store energy in electronic circuits, from simple filters to complex power supplies.
Common Charge Reference Values
| Source | Charge |
|---|---|
| Smartphone battery (3000 mAh at 3.7 V) | 10,800 C |
| AA battery charge (~2.5 Ah) | 9,000 C |
| Car battery (50 Ah at 12 V) | 180,000 C |
| Capacitor flash (100 μF at 300 V) | 30 mC |
| Lightning bolt (typical) | 15 C |
| 1 coulomb (6.24×10¹⁸ electrons) | 1 C |
| Static electricity spark | 1 μC |
| Laptop battery (50 Wh at 11.1 V) | 16,200 C |
Related Calculators
Authoritative References
Frequently Asked Questions
What is electric charge?
Electric charge is a fundamental property of matter that causes electromagnetic interactions. It is measured in coulombs (C). The charge stored in a capacitor is proportional to its capacitance and the applied voltage: Q = C × V, where Q is charge, C is capacitance in farads (F), and V is voltage in volts (V).
How do I calculate charge stored in a capacitor?
Charge is calculated using Q = C × V. For example, a 100 μF capacitor charged to 12 V stores Q = 100 × 10⁻⁶ × 12 = 0.0012 C = 1.2 mC. This represents approximately 7.5 × 10¹⁵ electrons. The energy stored can then be found using E = ½CV².
What is a farad?
A farad (F) is the SI unit of capacitance. One farad stores one coulomb of charge per volt: 1 F = 1 C/V. In practice, farad is very large; most capacitors are measured in microfarads (μF, 10⁻⁶ F), nanofarads (nF, 10⁻⁹ F), or picofarads (pF, 10⁻¹² F). Supercapacitors can reach several farads.
What is the difference between charge and energy in a capacitor?
Charge (Q = CV) represents the total electric charge stored, measured in coulombs. Energy (E = ½CV²) represents the work required to charge the capacitor, measured in joules. While charge depends linearly on voltage, energy depends on voltage squared — doubling voltage doubles the charge but quadruples the energy.
How does a capacitor store charge?
A capacitor consists of two conductive plates separated by an insulator (dielectric). When voltage is applied, electrons accumulate on one plate (negative) and are depleted from the other (positive). The dielectric material polarizes, allowing more charge storage. The capacitance depends on plate area, distance between plates, and dielectric material.
What is the relationship between charge and current?
Current is the rate of flow of electric charge: I = dQ/dt. One ampere equals one coulomb per second. A capacitor charging at 1 A receives 1 coulomb of charge every second. The voltage across the capacitor rises linearly with accumulated charge: V = Q/C.