Capacitance Calculator

C = Q/V or parallel-plate C = ε₀A/d. Compute capacitance, charge stored, or energy.

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General calculation reads

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How to use this calculator

  • Pick the mode.
  • Enter the appropriate quantities.
  • Read capacitance in F, µF, nF, pF.

About this calculator

Capacitance C measures how much charge a capacitor stores per volt: C = Q/V. For parallel plates: C = ε₀A/d (ε₀ is vacuum permittivity, 8.854 × 10⁻¹² F/m). Real capacitors use dielectric materials between plates which multiply C by a relative permittivity κ.

Frequently asked

Why is the Farad such a large unit?+
1 F is 1 Coulomb per Volt — an enormous amount of charge per volt. Most circuits use µF (10⁻⁶ F), nF (10⁻⁹ F), or pF (10⁻¹² F).
What is a dielectric?+
An insulating material between capacitor plates that increases capacitance. Common: ceramic, plastic, electrolyte. Multiplies C by relative permittivity κ.
Energy stored?+
E = ½CV². A 1 µF cap charged to 100 V stores 0.005 J — small, but discharges very fast (high power).
Series vs parallel capacitors?+
Parallel: C = C₁ + C₂ (add). Series: 1/C = 1/C₁ + 1/C₂ (reciprocals add). Opposite of resistors.
Why is capacitance important?+
Filters, timing circuits (RC time constant), energy storage (super-caps), AC coupling, and decoupling supply rails on every IC.

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