Capacitance Calculator — Parallel Plate Formula
Compute the capacitance of a parallel plate capacitor from plate area, separation and dielectric material, then find the charge and energy stored at any voltage.
cm²
mm
Dielectric material
V
C = ε₀ × εᵣ × A / d (parallel plate formula)
- 1
Plate area in m²
100 × 10⁻⁴ = 0.01 - 2
Plate separation in m
1 × 10⁻³ = 0.001 - 3
Capacitance C = ε₀ × εᵣ × A ÷ d
8.8542e-12 × 1 × 0.01 ÷ 0.001 = 88.5419Result in pF (auto-scaled from farads).
How does this calculator work?
Capacitance of a parallel plate capacitor is C = ε₀εᵣA/d, where ε₀ = 8.854 × 10⁻¹² F/m, εᵣ is the dielectric constant, A is the plate area and d is the separation. Charge stored is Q = CV and energy is E = ½CV². Enter dimensions and material to get C, Q and E for any applied voltage.
Formula
How this is calculated
A parallel plate capacitor consists of two conductive plates of equal area A separated by a distance d, with a dielectric material between them. The capacitance is C = ε₀ × εᵣ × A / d, where ε₀ = 8.854 × 10⁻¹² F/m is the permittivity of free space and εᵣ is the relative permittivity (dielectric constant) of the material between the plates — 1 for air or vacuum, about 3.5 for paper, 4.5 for glass and up to 80 for water at room temperature. A larger plate area and a smaller separation both increase capacitance; a higher dielectric constant increases it proportionally.
With an applied voltage V, the capacitor stores charge Q = C × V on the plates (positive on one, negative on the other). The electrical potential energy stored in the electric field between the plates is E = ½CV² (equivalently ½QV or Q²/2C). The energy grows quadratically with voltage — doubling the voltage quadruples the stored energy, which is why high-voltage capacitors must be handled carefully.
This formula assumes ideal parallel plates (uniform electric field, no fringing at the edges, no resistive or inductive losses). Real capacitors also exhibit parasitic inductance and resistance, and the effective capacitance can change with frequency, temperature and applied voltage — especially for electrolytic and ceramic types. The vacuum permittivity ε₀ used here is the exact CODATA 2018 value.
Frequently asked questions
Capacitance is directly proportional to plate area (C ∝ A). Doubling the area doubles the capacitance, because a larger area can accommodate more charge for the same electric field strength and voltage.
A dielectric material polarises in response to the electric field, reducing the effective field inside the capacitor. This allows more charge to be stored for the same applied voltage, increasing capacitance by a factor of εᵣ compared to vacuum.
The energy stored in a capacitor's electric field is E = ½CV² joules. It grows quadratically with voltage: doubling the voltage quadruples the energy stored. This energy can be released almost instantaneously, which is why capacitors are used in flash units, pulsed lasers and power supply filters.
TG we-Calculate Editorial Team. (2026). Capacitance Calculator — Parallel Plate Formula [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/capacitance-calculator
TG we-Calculate Editorial Team. "Capacitance Calculator — Parallel Plate Formula." TG we-Calculate. 2026. https://we-calculate.com/calculator/capacitance-calculator.
TG we-Calculate Editorial Team, "Capacitance Calculator — Parallel Plate Formula," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/capacitance-calculator
@misc{wecalculate_capacitance_calculator, title = {Capacitance Calculator — Parallel Plate Formula}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/capacitance-calculator}}, year = {2026}, note = {TG we-Calculate} }
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