Joules to Volts Calculator
Convert energy in joules (J) to electric potential in volts (V). Enter the energy in joules and the charge in coulombs, then press Calculate — the voltage result appears in volts, divided straight from V = E / Q. Everything runs locally in your browser.
Enter energy in joules
Type the energy E in joules (J) — the work done or electric potential energy involved. Zero joules is fine and gives 0 V.
Enter charge in coulombs
Type the charge Q in coulombs (C). It must be a non-zero number, because the voltage divides the energy by the charge.
Press Calculate, read volts
The voltage V appears in volts (V), shown to at most ten significant digits. Copy the result to your clipboard, or press Reset to clear everything and start over.
How joules become volts
- What is the joules-to-volts formula?
- The voltage V in volts (V) is equal to the energy E in joules (J), divided by the charge Q in coulombs (C): V(V) = E(J) / Q(C). One volt is one joule of energy per coulomb of charge.
- Worked example
- If 12 J of energy is expended moving a charge of 3 C, the voltage is V = 12 J / 3 C = 4 V. Likewise 9 J across 4 C gives 9 / 4 = 2.25 V.
- Why does zero charge give an error?
- V = E / Q divides by the charge, and division by zero is undefined — with no charge there is no potential difference to speak of. A charge of exactly 0 C is rejected instead of showing a meaningless infinite result. Zero energy, on the other hand, is valid: 0 J / Q C = 0 V.
- What about negative values?
- The arithmetic is defined for negative energy or negative charge (V = −12 J / 3 C = −4 V), which corresponds to energy released in the opposite direction of the charge flow. Both compute here rather than being rejected.
- How accurate is the result?
- Results are computed in standard double-precision arithmetic and displayed with at most ten significant digits with floating-point noise trimmed, so 12 / 3 shows as exactly 4 and 10 / 3 as 3.333333333.
Privacy: every calculation runs in your browser tab — no value you type is sent anywhere. Copy result uses your clipboard only. Results are ideal circuit-theory figures; verify real installations with a multimeter.