Choose parallel plate, series, parallel, RC time, or energy.
Each mode uses different inputs — fill the ones for your selected mode.
See capacitance in F, µF, nF, pF plus mode-specific outputs.
A parallel-plate capacitor's capacitance is proportional to plate area and dielectric constant, inversely proportional to plate separation. Capacitors in series combine like resistors in parallel (the total is less than the smallest); capacitors in parallel combine additively. The RC time constant tells you how fast a capacitor charges or discharges through a resistor — voltage reaches 63% in 1τ and 99% in 5τ. Stored energy scales with the square of voltage.
C = ε₀εᵣA/d • Series: 1/C = Σ1/Cᵢ • Parallel: C = ΣCᵢ • τ = RC • E = ½CV²
Series capacitors: total capacitance is always LESS than the smallest individual capacitor
Parallel capacitors: total capacitance is the SUM of all individual capacitors
RC time constant τ = R × C — voltage reaches 63% of final in 1τ, 99% in 5τ
Stored energy E = ½CV² scales with voltage² — doubling V quadruples energy
Common dielectric constants: vacuum 1, air 1.0006, glass ~5, water 80, ceramic 10-3000
Capacitors in series increase voltage rating; in parallel they increase capacitance
Electrolytic capacitors are polarized — connect them backwards and they fail catastrophically
Capacitors are among the most widely used passive components in electronics, appearing in everything from smartphone power supplies to industrial motor drives. A single circuit board may contain hundreds of capacitors performing filtering, energy storage, timing, coupling, and decoupling functions. Calculating capacitance correctly is essential for circuit performance — an undersized filter capacitor causes excessive ripple, while an oversized one wastes board space and budget. The parallel-plate capacitance formula C = epsilon-zero times epsilon-r times A divided by d governs basic capacitor physics, but real-world design also requires computing series and parallel combinations, RC time constants for timing circuits, and stored energy for power supply hold-up calculations. Common capacitance values span twelve orders of magnitude, from single-digit picofarads in RF circuits to thousands of microfarads in audio amplifiers. This capacitance calculator handles all five core calculations — parallel-plate sizing, series combinations, parallel combinations, RC time constants, and energy storage — and reports results in farads, microfarads, nanofarads, and picofarads simultaneously.
Capacitors store electrical energy in an electric field between two conductors. They're used everywhere — smoothing power supply ripple, coupling AC signals between stages, blocking DC, setting timing in oscillators and filters, providing burst energy for camera flashes and motor starting. Understanding capacitance lets you size capacitors correctly for any of these applications without trial and error.
One thing that trips up new electronics engineers: capacitors combine the OPPOSITE way from resistors. Resistors in series add; capacitors in series combine like resistors in parallel (smaller). Resistors in parallel combine like 1/(1/R₁+1/R₂); capacitors in parallel just add. If you ever forget, remember that series capacitors are 'pulled apart' by the geometry, reducing effective capacitance, while parallel capacitors stack effective area, increasing it.
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All formulas verified against official standards.