Capacitor Capacitance Calculator (Circuit & Design)
Calculate capacitance using charge/voltage or physical dimensions/dielectrics. Features a material database and visual formula reference for engineers.
About
Capacitance measures a component's ability to store electrical charge per unit of voltage. In circuit analysis, this is a straightforward relationship between charge and potential difference. However, for hardware engineers and physicists designing capacitors, the geometry and material properties are paramount. The capacitance is directly proportional to the surface area of the plates and the permittivity of the dielectric material between them, while being inversely proportional to the distance separating the plates.
This tool allows users to toggle between these two fundamental modes. Design Mode is particularly useful for PCB designers or hobbyists creating custom capacitors, providing a database of relative permittivity (εr) for common insulators like Ceramic, Mica, and Polypropylene. Accurate calculation prevents circuit instability and ensures proper energy storage in power supply filtering or timing applications.
Formulas
Mode 1: Circuit Definition
Where Q is charge in Coulombs and V is Voltage.
Mode 2: Physical Design
Where εr is the material's relative permittivity, ε0 is the vacuum permittivity (8.854 × 10-12 F/m), A is plate area, and d is distance.
Reference Data
| Material (Dielectric) | Relative Permittivity (εr) | Dielectric Strength (MV/m) |
|---|---|---|
| Vacuum / Air | 1.0006 | 3.0 |
| Polypropylene | 2.2 − 2.36 | 24 |
| Polyester (Mylar) | 3.1 − 3.2 | 16 |
| Paper | 3.0 − 4.0 | 16 |
| Glass | 3.7 − 10.0 | 9 − 14 |
| Mica | 4.0 − 8.0 | 118 |
| Ceramic (Class 1) | 10 − 100 | Var |
| Water (Distilled) | 80.1 | 65 − 70 |