Capacitance describes how much electric charge a component can store for each volt applied across it, and it sits at the heart of almost every circuit that smooths power, filters signals, sets timing or stores energy. This calculator gives you two clear ways to find it. The first works straight from the physics of stored charge: divide the charge in coulombs by the voltage in volts and you have the capacitance in farads, the most direct expression of what a capacitor actually does. The second works from physical geometry, letting you size or check a parallel-plate capacitor from its plate area, the gap between the plates, and the relative permittivity of whatever material fills that gap. Because a farad is an enormous unit in everyday electronics, the calculator also expresses every result in microfarads, nanofarads and picofarads, which are the values you will actually read off a real component or a circuit diagram. You can switch between the two modes with a single dropdown, and only the inputs that matter for your chosen method are shown, so there is nothing to clutter the screen or confuse the result. The permittivity of free space is built in at its standard value, and the relative permittivity defaults to 1 for a vacuum or air, which you can raise for a dielectric. Whether you are a student checking homework, a hobbyist designing a filter, or an engineer verifying a stored-charge figure, the calculator returns a transparent answer you can trace back to the formula. Enter your values below and the result updates instantly as you type.
From stored charge, capacitance is the charge divided by the voltage: C = Q / V, where Q is in coulombs, V is in volts and C is in farads. From parallel-plate geometry, C = ε₀ × εr × A / d, where ε₀ is the permittivity of free space (about 8.854 × 10⁻¹² farads per metre), εr is the relative permittivity of the material between the plates (1 for vacuum or air), A is the plate area in square metres, and d is the separation in metres.
C = Q / V (charge and voltage)
C = ε₀ × εr × A / d (parallel plate)
A capacitor stores 0.001 coulombs of charge when 5 volts is applied across it. Its capacitance is 0.001 / 5 = 0.0002 farads. That is the same as 200 microfarads, 200,000 nanofarads, or 200,000,000 picofarads.
This calculator is for students, hobbyists, technicians and engineers who need to find a capacitor's value, either from the charge it stores at a given voltage or from the physical size and spacing of its plates.
Capacitance is the charge stored per unit of voltage, so C = Q / V in farads. For a parallel-plate capacitor you can also use C = ε₀ × εr × A / d.
A farad is the unit of capacitance. One farad stores one coulomb per volt. Because that is very large, real capacitors are rated in microfarads, nanofarads or picofarads.
Multiply farads by one million for microfarads, one billion for nanofarads, and one trillion for picofarads. So 0.0002 F is 200 µF.
It is about 8.854 × 10⁻¹² farads per metre, written ε₀. It appears in the parallel-plate formula, multiplied by the relative permittivity of the material between the plates.
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