Volt to Electron Volt Calculator

How to use the volts to electron volts calculator

What this calculator does

This calculator converts a potential difference and an electric charge into energy. It evaluates the electrical-energy identity E = qV, reports the result in joules, and then expresses the same energy in electron volts. It is useful for particle physics, electronics, radiation work, and classroom problems where charge may be stated either as a number of elementary charges or in coulombs. The result is an exact unit conversion for the entered values; it does not model losses, circuit resistance, particle collisions, or how a real device distributes energy.

When to use it

Use the calculator when you need to find the energy gained by electrons or ions crossing a voltage, translate a laboratory charge-and-voltage calculation into electron volts, verify a homework solution, or compare microscopic energy scales with the SI joule. The NIST SI reference for the electronvolt defines 1 eV as exactly 1.602176634 × 10 ^{– 19} J under the current SI.

How to calculate

1. The calculator opens with a ready-to-use demonstration: 36 V and 30 e. The live result is already calculated, and the example Excel workbook is immediately available.
2. Replace the number in Voltage, then choose the matching Voltage unit: mV, V, kV, or MV. Changing the unit converts the current entry rather than merely relabeling it.
3. Enter the nonnegative magnitude in Electric charge, then choose the Charge unit: e, C, mC, μC, or nC. Scientific notation such as 1.602176634e – 19 is accepted.
4. Read Energy (electron volts) as the main result. Use Energy (joules), Charge in coulombs, Charge in elementary units, and Canonical voltage to audit the conversion.
5. Select Download Excel to export the current inputs, outputs, formulas, units, and calculation notes as a validated XLSX workbook. Reset clears the demonstration and all calculated content; Excel export remains disabled until a complete valid state is entered again.

Input guide

Voltage is a required signed decimal value representing electric potential difference. It accepts ordinary decimals, correctly grouped thousands, or scientific notation; for example, 36, 1,250.5, or 2.5e3. Its selected unit is controlled by Voltage unit. A higher voltage increases the magnitude of energy in direct proportion when charge is unchanged. A negative voltage produces negative potential-energy change. Do not type ambiguous decimal-comma values such as 1,5; use 1.5.

Voltage unit is required and selects millivolts, volts, kilovolts, or megavolts. The calculator converts the displayed number when you switch units, so 36 V becomes 0.036 kV without changing the underlying potential difference. A common mistake is to change the unit and then re-enter a separately converted value, which applies the conversion twice.

Electric charge is a required nonnegative decimal magnitude. A realistic microscopic example is 30 e; a macroscopic example might be 2 μC. Zero is valid and produces zero energy. Negative charge counts are rejected because this field represents charge magnitude; use the sign of Voltage when a signed energy change is needed.

Charge unit is required. The option e means multiples of the elementary charge, while C, mC, μC, and nC are coulomb-based units. Switching the unit converts the current value using the exact elementary charge. The NIST CODATA value for the elementary charge confirms e = 1.602176634 × 10 ^{– 19} C exactly.

Output guide

Energy (electron volts) is the primary conversion result. It is driven by canonical voltage and charge: E(eV) = V(V) × q(C) ÷ e(C). When charge is entered directly in elementary units, this simplifies to E(eV) = V × charge count. Zero means either voltage or charge is zero; a negative result indicates a negative potential-energy change. Energy (joules) is the identical energy in the SI unit and follows E(J) = V × q(C).

Charge in coulombs and Charge in elementary units show the same charge in both supported base representations. Canonical voltage shows the selected voltage converted to volts. The summary pills repeat the current voltage, charge, electron-volt energy, and joule energy for quick scanning. In the Conversion detail table, the columns Quantity, Current value, Unit, and Interpretation provide an audit trail; they do not introduce a different model or additional assumptions.

Worked example

With the startup values, voltage is 36 V and charge is 30 elementary charges. Because one unit of elementary charge crossing one volt gains one electron volt, the calculation is 36 × 30 = 1,080 eV. The charge in coulombs is 30 × 1.602176634 × 10 ^{– 19} = 4.806529902 × 10 ^{– 18} C. Multiplying that charge by 36 V gives 1.73035076472 × 10 ^{– 16} J, displayed as 1.730351e – 16 J. Multiplying 1,080 eV by the exact joule-per-electronvolt factor produces the same value.

Learn more

For the broader unit framework, consult the BIPM SI Brochure, the international reference for SI definitions and accepted units. Electron volts are especially convenient for atomic and subatomic scales because joule values become extremely small, while joules remain preferable for SI-based engineering calculations.