Electronics · Physics
Capacitance Calculator
Compute capacitance from geometry or a component network, then derive charge, energy, time constant, and reactance.
Capacitance Source
Choose how the total capacitance is derived
Dielectric
Sets relative permittivity εᵣ — ceramics vary too widely to preset reliably
Relative Permittivity (εᵣ)
Dielectric constant relative to vacuum
Plate Area
cm²
Overlapping area of each plate
Plate Separation
mm
Distance between the plates
⚡ Circuit Parameters
Voltage
V
Voltage across the capacitor
Resistance
Ω
Series resistance, for RC time constant
Frequency
Hz
AC signal frequency, for capacitive reactance
Capacitive
Dominance 0%
Dominance 0%
Total Capacitance
0 F
at the given configuration
Charge Stored (Q = CV)
0 C
Energy Stored (E = ½CV²)
0 J
RC Time Constant (τ = RC)
0 s
Capacitive Reactance (Xc)
0 Ω
📊 Calculation Breakdown
| Quantity | Value | Note |
|---|
Governing equations
C = ε₀εᵣA/d | Q = CV | E = ½CV² | τ = RC | Xc = 1/(2πfC)
- Parallel Plate: C = ε₀ · εᵣ · A ÷ d, where ε₀ = 8.854×10⁻¹² F/m
- Series Network: 1/C_total = 1/C₁ + 1/C₂ + … — total is always less than the smallest capacitor
- Parallel Network: C_total = C₁ + C₂ + … — capacitances simply add
- RC Time Constant (τ): time to charge/discharge to ~63.2% of the voltage difference
- Capacitive Reactance (Xc): effective "resistance" to AC current, decreasing as frequency or capacitance increases
⚠️ This models an idealized, lossless capacitor. Real components have tolerance, ESR, dielectric absorption, temperature drift, and voltage/frequency-dependent behavior not captured here — check the datasheet for design-critical work.