Calculators
Capacitance Calculator
Calculate capacitance, charge, or voltage using Q = CV.
Solve the ideal capacitor relationship Q = C × V for capacitance, stored charge, or voltage.
Result
10 µF
Ideal relationship: Q = C × V. Capacitance is in farads, charge in coulombs, and voltage in volts after unit conversion.
About This Tool
Capacitance describes how much electric charge an ideal capacitor stores per volt of potential difference. This calculator solves the fundamental relationship Q = C × V for any one of its three quantities: capacitance C, charge Q, or voltage V. It is useful for electronics study, capacitor calculations, and checking unit conversions. All calculations run locally in your browser.
How To Use It
- Choose whether to calculate capacitance, charge, or voltage.
- Enter the two known quantities and select their units.
- Read the result in the selected unit; the calculator converts values through SI units internally.
- Use the result as an ideal capacitor calculation and check real component ratings, tolerance, dielectric behavior, and safety separately.
Examples
Find capacitance
If a capacitor stores 50 µC at 5 V, C = Q/V = 50 µC ÷ 5 V = 10 µF.
Find stored charge
A 4.7 µF capacitor at 5 V has ideal charge Q = CV = 23.5 µC.
Find voltage
If 50 µC is stored on a 10 µF capacitor, V = Q/C = 5 V.
Useful Notes
Capacitance formula
The defining ideal relationship is Q = C × V. Rearranging gives C = Q/V and V = Q/C. In SI units, one farad equals one coulomb per volt.
Common capacitance units
The farad is large for many practical components, so capacitors are commonly labeled in millifarads (mF), microfarads (µF), nanofarads (nF), or picofarads (pF). The calculator converts these prefixes before solving the equation.
Charge and voltage signs
The algebraic relationship can use signed charge and voltage. In many component-sizing examples magnitudes are used. The physical sign depends on which capacitor plate and voltage reference are being described.
Ideal capacitor assumption
Q = CV treats capacitance as a fixed value. Real capacitors have tolerance, leakage, equivalent series resistance, voltage coefficients, temperature effects, dielectric absorption, and maximum voltage ratings that this basic calculator does not model.
Division by zero
Calculating capacitance requires non-zero voltage, and calculating voltage requires non-zero capacitance. The calculator reports these undefined cases rather than returning an infinite result.
FAQ
What does one farad mean?
One farad is the capacitance that stores one coulomb of charge for one volt of potential difference: 1 F = 1 C/V.
Is µF the same as uF?
Yes in ordinary electronics notation. µF is the SI-symbol form for microfarad, while uF is commonly typed when the micro symbol is inconvenient.
Does this calculate capacitor energy?
No. This tool focuses on Q = CV. Capacitor energy uses a different relationship, such as E = 1/2 CV².
Can this select a safe capacitor for a real circuit?
No. A numerical capacitance result does not determine safe voltage rating, dielectric type, tolerance, ripple-current capability, temperature range, polarity, or other component requirements.
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