Convert Joules to Volts Online

Converting Joules to Volts

Voltage is not a direct energy unit, but you can calculate voltage when you know the energy stored or transferred and the electric charge involved. This relationship comes from the definition of the volt: one volt equals one joule per coulomb. The calculator accepts energy and charge in multiple units and returns voltage instantly.

The Voltage Formula

The fundamental relationship is:

$$V = \frac{E}{Q}$$

Where $V$ is voltage in volts, $E$ is energy in joules, and $Q$ is electric charge in coulombs.

Worked Example

Suppose a capacitor stores 1,000 J of energy and holds 10 C of charge:

$$V = \frac{1000\ J}{10\ C} = 100\ V$$

Unit Support

Energy can be entered in joules, kilojoules, watt-hours, calories, or electronvolts. Charge can be entered in coulombs, millicoulombs, microcoulombs, or ampere-hours. All values are normalized to base SI units before the calculation runs.

Related Electrical Tools

Explore the Capacitance Converter for capacitor values, the Energy Converter for broader energy unit changes, or the Electricity Calculator for voltage-current-resistance relationships.

Frequently Asked Questions

How do I convert joules to volts?

Divide the energy in joules by the charge in coulombs. For example, 500 J with 5 C gives 100 V.

What is the voltage when there is 1,000 J with 10 C?

The voltage is 100 V, calculated as 1,000 ÷ 10.

Can joules be directly converted to volts without charge?

No. Volts measure potential difference per unit charge. You need both energy and charge (or capacitance and energy) to find voltage.

What units of charge does this calculator support?

Coulombs, millicoulombs, microcoulombs, nanocoulombs, ampere-hours, and milliampere-hours. All are converted to coulombs internally.

Is negative voltage possible?

Yes. Negative voltage indicates direction of electric field or charge flow relative to a reference point. This calculator assumes positive energy and charge inputs.

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Joules to Volts Calculator