Capacitance Calculator
Calculate capacitance from charge and voltage (C=Q/V), energy stored (½CV²), parallel plate capacitance, and series/parallel combinations. Includes RC time constant.
Capacitance (μF)
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Capacitance (nF) —
Capacitance (pF) —
Energy Stored (μJ) —
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Capacitance (μF)
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Energy Stored (J) —
Professional Full parameters & maximum detail ▾
Capacitor Combinations
Series Capacitance (μF) —
Parallel Capacitance (μF) —
RC Circuit
RC Time Constant τ (ms) —
Impedance Xc at freq (Ω) —
How to Use This Calculator
- Enter Charge Q (μC) and Voltage V to calculate capacitance and energy stored.
- Use the Parallel Plate tab to compute capacitance from plate dimensions and dielectric material.
- Use the Energy Stored tab starting from capacitance and voltage.
- The Professional tab calculates series/parallel combinations and RC time constant.
Formula
C = Q/V | Energy = ½CV² | Parallel plate: C = κε₀A/d
Series: 1/C = 1/C₁ + 1/C₂ + ... | Parallel: C = C₁ + C₂ + ...
Example
Q=10 μC, V=5 V → C = 2 μF, Energy = ½×2×10⁻⁶×25 = 25 μJ.
Frequently Asked Questions
- Capacitance is the ability of a component to store electric charge. C = Q/V, where Q is charge in coulombs and V is voltage. The unit is Farads (F). 1 μF = 10⁻⁶ F.
- Energy E = ½CV². A 100μF capacitor charged to 12V stores E = ½ × 100×10⁻⁶ × 144 = 0.0072 J = 7.2 mJ.
- C = κε₀A/d, where κ is the dielectric constant, ε₀ = 8.854×10⁻¹² F/m, A is plate area in m², and d is separation in m.
- 1/C_total = 1/C1 + 1/C2 + 1/C3. The total series capacitance is always less than the smallest individual capacitor.
- τ = R × C. After one time constant, a capacitor charges to 63.2% of supply voltage (or discharges to 36.8%). After 5τ it is essentially fully charged/discharged.