Capacitance Calculator
Enter the known values and run the calculation.
Calculate capacitance from dielectric constant, plate area, and plate spacing.
Choose whether you want to solve for capacitance, plate area, plate spacing, or relative permittivity.
Enter the known values, choose the engineering units that match the geometry on your bench or drawing, and run the calculation. The result card reports the solved value plus the SI-normalized terms behind it.
Overview
Estimate capacitance from geometry and dielectric assumptions for basic capacitor work.
Use this tool to solve the ideal parallel-plate relationship for capacitance or for any one of the surrounding geometry terms.
Use it for first-pass dielectric sizing, illustrating the relationship between area and spacing, and quick feasibility checks before moving to real dielectric data or component datasheets.
The math and how it's used
Rearranged for plate area: A = (C * d) / (epsilon_r * epsilon_0).
Rearranged for plate spacing: d = (epsilon_r * epsilon_0 * A) / C.
Rearranged for relative permittivity: epsilon_r = (C * d) / (epsilon_0 * A).
This is the ideal parallel-plate relationship. It does not model fringing fields, real dielectric loss, multilayer geometry, or stray capacitance.
This is the parallel-plate capacitance model engineers use for first-pass geometry checks, dielectric comparisons, and sanity checks on sensor or fixture layouts.
It is intentionally idealized. Fringing fields, multilayer stacks, dielectric loss, and nearby conductors can shift the real capacitance enough that bench data or field solving becomes the better next step.
What this assumes
This is the ideal textbook form for a uniform dielectric between simple plates. Real capacitors add fringing fields, construction details, dielectric tolerance, ESR, leakage, and package parasitics.
Use this as the planning number. If a real capacitor choice matters, check the vendor datasheet and the actual dielectric and package style.