Joules to Volts Calculator

Q: Can you convert joules to volts directly?

Only if you also know the charge. Joules measure energy and volts measure energy per unit charge, so V = J ÷ C.

Q: How many volts is 1 joule per coulomb?

Exactly 1 volt. That is the definition of the volt.

Q: How do I find voltage from energy and amp-hours?

Convert amp-hours to coulombs by multiplying by 3,600, then divide the energy in joules by that number.

Convert joules to volts using charge: V = E ÷ Q. Find the voltage when you know the energy transferred and the charge in coulombs.

⚡ ENERGY

🔋 CHARGE

VOLTAGE

12 V

FORMULA

V = J / C

ENERGY IN Wh

0.033 Wh

💡 How to Convert Joules to Volts

To convert joules to volts, divide the energy in joules by the charge in coulombs. This comes straight from the definition of the volt: one volt is one joule of energy per coulomb of charge.

Joules to volts formula

V = E ÷ Q

V = voltage in volts, E = energy in joules, Q = charge in coulombs
Example: 120 J ÷ 10 C = 12 V

Worked examples

Physics problem: 9 J of work moves 6 C of charge between two points, so the potential difference is 9 ÷ 6 = 1.5 V.
Battery check: a battery delivers 86,400 J while supplying 2 Ah (7,200 C), so its average voltage was 86,400 ÷ 7,200 = 12 V.
From electronvolts: an electron (1.602 × 10⁻¹⁹ C) gains 1.602 × 10⁻¹⁶ J, so it passed through 1,000 V, i.e. it gained 1 keV.

Joules to volts table

Energy (J)	Charge (C)	Voltage (V)
1	1	1
9	6	1.5
120	10	12
1,000	100	10
13,500	9,000	1.5
86,400	7,200	12
432,000	36,000	12
1,000,000	1,000	1,000

The units behind the formula

Joule (J): the SI unit of energy. 1 J = 1 watt for 1 second = 1 volt × 1 coulomb.
Volt (V): electric potential difference, defined as 1 joule of energy per coulomb of charge.
Coulomb (C): electric charge. One coulomb is the charge carried by a current of 1 ampere in 1 second, about 6.242 × 10¹⁸ electrons.
Watt (W): power, the rate of energy transfer. 1 W = 1 J per second.

When you know power and current instead

If you know power in watts and current in amps rather than energy and charge, use V = P ÷ I with the watts to volts calculator. It is the same relationship per second: watts are joules per second and amps are coulombs per second.

Related conversions: volts to joules · joules to watts · capacitance to charge

Volts = joules ÷ coulombs. 120 J ÷ 10 C = 12 V.