Primary formula
C = Q / V; Q = C x V; E = 1/2 x C x V^2.
Physics calculator
Capacitance Calculator
Calculate capacitance from charge and voltage, or solve capacitor charge and ideal stored energy.
Last reviewed: July 21, 2026Physics formula engine v3.0.0
Physics calculator
Capacitance Calculator
Enter values, select units and calculate locally. Results use SI internally and show rounded display values.
Decimal.js physics math
Mode
Find capacitance from charge and voltage.
Result and visual stay hidden until you choose Calculate.
Formula and assumptions
Input assumptions
Capacitance is positive. Voltage cannot be zero when solving capacitance. The component is treated as an ideal capacitor.
Precision note
Physics calculators convert compatible inputs into SI units before calculating. Decimal.js is used for arithmetic where practical; trigonometric angle factors are rounded for display.
Physics calculation flow
Parse
Read labelled inputs, selected units and calculation mode from the calculator card.
Convert
Convert compatible values to SI base or derived units without calling external services.
Calculate
Apply the selected deterministic mechanics formula and validate against NaN, Infinity and invalid divisors.
Label
Display the result, supporting unit rows, formula steps, warnings and dynamic visual below the input card.
What Capacitance Calculator does
Use this calculator for ideal capacitor relationships in basic circuits and physics examples.
The calculator is deterministic and runs from manual inputs only. It is a physics formula tool, so it should not be confused with a unit converter that only changes labels after a value is already known.
Formula and variables
C = Q / V; Q = C x V; E = 1/2 x C x V^2.
The calculator converts supported units into SI base or derived units for the actual calculation, then formats the result in the selected display unit.
- C is capacitance
- Q is charge
- V is voltage
- E is stored energy
Worked examples
Use the examples below to check expected order of operations and unit handling before applying the tool to your own values.
- 0.002 C / 10 V = 0.0002 F
- 100 uF x 12 V = 0.0012 C
- 0.5 x 100 uF x 12^2 = 0.0072 J
Unit conversions
Length, time, mass, area, volume, speed, force, pressure, density, frequency, energy and power units reuse the central NexaCalc conversion registry. Acceleration, angle and spring-constant units use the same SI-first convention where applicable.
The displayed conversion rows are supporting context. They do not change the physical assumptions of the selected formula.
Common mistakes
Most errors come from mixing physical quantities that sound similar in everyday language or choosing a unit that belongs to a different dimension.
- Forgetting microfarad conversion.
- Using zero voltage to solve capacitance.
- Treating ideal stored energy as a safety rating.
Assumptions and limitations
This page is intended for educational and planning calculations, not professional engineering certification.
This calculator uses idealized physics formulas and the input values you provide. Real systems may require additional effects such as friction, drag, rotation, deformation, losses or measurement uncertainty.
- Capacitance is positive.
- Voltage cannot be zero when solving capacitance.
- The component is treated as an ideal capacitor.
- Leakage, ESR, dielectric strength, tolerance and frequency response are not modeled.
- Capacitor safety requires rating and discharge checks.
Frequently asked questions
How is capacitance calculated?
Capacitance Calculator uses C = Q / V; Q = C x V; E = 1/2 x C x V^2. The result is calculated from the values and units entered in the form.
How do I calculate capacitor charge?
Capacitance Calculator uses C = Q / V; Q = C x V; E = 1/2 x C x V^2. The result is calculated from the values and units entered in the form.
How do I calculate stored energy in a capacitor?
Capacitance Calculator uses C = Q / V; Q = C x V; E = 1/2 x C x V^2. The result is calculated from the values and units entered in the form.
Why is capacitance measured in farads?
Use this calculator for ideal capacitor relationships in basic circuits and physics examples. Capacitance is positive.
What is the difference between uF, nF and pF?
Capacitance Calculator is formula-based. Use the related calculator when the question changes physical quantity, and use Conversion tools only when the value is already known.
Can voltage be zero when solving capacitance?
Capacitance Calculator allows signed results only where the physics quantity can carry direction or reference-sign meaning. Divisors such as time, mass and gravity are validated before calculation.
Does this calculator model parallel plate geometry?
Capacitance Calculator uses an idealized classroom physics model. Leakage, ESR, dielectric strength, tolerance and frequency response are not modeled.
Does stored energy mean the capacitor is safe to touch?
Use this calculator for ideal capacitor relationships in basic circuits and physics examples. Capacitance is positive.
How does capacitance relate to Coulomb's Law?
Use this calculator for ideal capacitor relationships in basic circuits and physics examples. Capacitance is positive.
When should I use a circuit simulator?
Use this calculator for ideal capacitor relationships in basic circuits and physics examples. Capacitance is positive.
References
- NIST Special Publication 811, Guide for the Use of the International System of Units. Relevance: SI unit symbols and derived-unit naming. Last verified: July 21, 2026. Source.
- BIPM, The International System of Units SI Brochure. Relevance: SI base and derived units used in mechanics, fluids, waves and optics. Last verified: July 21, 2026. Source.
- OpenStax University Physics Volume 1. Relevance: introductory formulas for motion, force, work, energy, momentum, fluids, waves and optics. Last verified: July 21, 2026. Source.
- NIST CODATA internationally recommended values. Relevance: physical constants for electricity, modern physics, gravitation and radiation formulas. Last verified: July 21, 2026. Source.
- OpenStax University Physics Volume 2. Relevance: electric circuits, capacitance, magnetic force and electromagnetic waves. Last verified: July 21, 2026. Source.
- OpenStax University Physics Volume 3. Relevance: photons, nuclear decay and blackbody radiation concepts. Last verified: July 21, 2026. Source.
Physics references verified for SI units, mechanics, fluids, waves, sound and optics formulas on July 21, 2026.
Educational disclaimer
This calculator provides mathematical results from the values, conventions and methods you enter. Verify important academic, engineering or professional work independently.