Joules to Volts Calculator — Convert Energy to Voltage (V = E ÷ Q)
Voltage and energy measure different physical quantities — a direct unit conversion does not exist. But given the electric charge (in coulombs), you can convert joules to volts using V = E / Q. Alternatively, enter current (A) and time (s) and the calculator derives Q = I × t first.
J
Convert via
C
V = E ÷ Q — voltage equals energy divided by charge
- 1
Charge Q
5 C - 2
Voltage V = E ÷ Q
100 ÷ 5 = 20One volt is defined as one joule per coulomb (1 V = 1 J/C).
How does this calculator work?
Joules to volts: V = E / Q, where E is energy in joules and Q is charge in coulombs. There is no direct unit conversion — charge is always needed. If you know current I (A) and time t (s), compute Q = I × t first, then V = E / (I × t). Enter energy plus charge (or I and t) to get the voltage.
Formula
How this is calculated
Voltage (electric potential difference) is defined as the energy transferred per unit of charge: V = E / Q, where E is energy in joules and Q is charge in coulombs. One volt is exactly one joule per coulomb (1 V = 1 J/C). This is a fundamental relationship in electrostatics and circuit analysis, not a simple unit scaling — you need to know the charge involved to convert between the two quantities.
If you know the current I (amperes) and the time t (seconds) that the current flowed, the charge is Q = I × t (coulombs), so V = E / (I × t). This form is especially useful for capacitor discharge and battery energy calculations. The power delivered during that time is P = E / t (watts).
Note that joules is a unit of energy, while volts is a unit of electric potential — they describe different physical concepts. This calculator computes voltage from a given energy and charge context; it does not perform a simple unit conversion the way, say, kilowatts to megawatts does.
Frequently asked questions
No — joules (energy) and volts (electric potential) measure different physical quantities. You always need the electric charge Q in coulombs to relate them: V = E / Q. If you know the current and time instead, use Q = I × t and then V = E / (I × t).
One coulomb is the charge transported by a current of 1 ampere in 1 second. A standard USB charger delivering 2 A transfers 2 coulombs of charge every second. An AA battery holds roughly 5,000–10,000 coulombs of charge (≈ 1.5 Ah × 3600 s/h).
A capacitor storing charge Q at voltage V holds energy E = ½QV = ½CV². Rearranging, V = 2E / Q. This calculator uses the non-capacitor form V = E / Q (applicable to a resistive circuit where all the energy is delivered at a constant voltage), so for capacitors the factor of ½ means the effective voltage is doubled. Use a dedicated capacitor energy calculator for that specific case.
TG we-Calculate Editorial Team. (2026). Joules to Volts Calculator — Convert Energy to Voltage (V = E ÷ Q) [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/joules-to-volts-calculator
TG we-Calculate Editorial Team. "Joules to Volts Calculator — Convert Energy to Voltage (V = E ÷ Q)." TG we-Calculate. 2026. https://we-calculate.com/calculator/joules-to-volts-calculator.
TG we-Calculate Editorial Team, "Joules to Volts Calculator — Convert Energy to Voltage (V = E ÷ Q)," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/joules-to-volts-calculator
@misc{wecalculate_joules_to_volts_calculator, title = {Joules to Volts Calculator — Convert Energy to Voltage (V = E ÷ Q)}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/joules-to-volts-calculator}}, year = {2026}, note = {TG we-Calculate} }
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