HomeCalculatorsElectricalPower & EnergyeV to Volts Calculator
Electrical calculator

eV to Volts Calculator

Relate electronvolt energy to electric potential difference through ΔE = qΔV. eV and volts measure different physical quantities. Runs locally in your browser.

Instant result
Result
—

Enter values to calculate.

Inputs—
Mode—
Formula—
Trust summary CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance
Input interpretation
Enter values to calculate.
Result
—
Assurance
Engineering
Declared partition coverage
PASS · 5/5 declared partitions (ev-v-e, ev-v-c, v-ev-e, v-ev-c, invalid-domain) · Matrix
Known limitations
  • Charge is magnitude |Q|; electron (−e) vs proton (+e) sign is not modeled. Not a pure eV↔V unit conversion.
  • Core CVP does not include live graph, viewport, or pointer interaction.
Model
Magnitude of the equivalent potential difference from electron-volt energy and charge (elementary-charge units or coulombs), or energy in eV from volts and charge.
Scope
Elementary charge e = 1.602176634×10⁻¹⁹ C exactly (SI defining constant; no uncertainty)
Verification
Engine tested · Source checked · v1.3.0 · CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance· View Manifest · CVP overview · Specification
Versions
Calculation 1.3.0 · CVP protocol 1.0.0-proposed · Evidence 2026-09-14.si-exact-e-zero-charge
Verification revision
2026-09-14.si-exact-e-zero-charge · 2/2 property · digest 99c55c4d8029
Legacy regression
21/21 tests · Production surface contract 3/3
Trust layers
Verification VERIFIED · Production CURRENT · overall VERIFIED
Reference
O1 model · O2 expected_values · O2 numerical_behavior
Interfaces
PASS · UI (SSR) / REST / MCP — ui-ssr is query-result HTML, not a live browser session.
Supplemental domain review
Not performed
Named expert review
Not performed
CVP suite
6/6 golden · 8/8 CVP boundary · 11/11 invalid · 2/2 property · 3/3 metamorphic · 1/1 round-trip · 3/3 cross-interface · 3/3 CVP contract · Manifest
Sources
Sources
Evidence
12 legacy golden · 5 legacy boundary · legacy regression suite · 6/6 oracle-backed golden · 11/11 invalid · Artifact integrity PASS
This calculator CURRENT · Public schema 1.3.0 matches · Semantic contract ✓ · Production attested · Public/cache ✓ · Origin ✓
Semantic contract
PASS
Full verification

Manifest identity, reference classes, interfaces, suite, and production records.

Formulas

Core equations used by this calculator.

eV → V (elementary charge)V = E(eV) ÷ Q(e)
eV → V (coulombs)V = 1.602176634×10⁻¹⁹ × E(eV) ÷ Q(C)
V → eV (elementary charge)E(eV) = V × Q(e)
V → eV (coulombs)E(eV) = V × Q(C) ÷ 1.602176634×10⁻¹⁹
iFor one elementary charge (Q = 1 e), 1 eV corresponds to 1 V of accelerating potential. Elementary charge e = 1.602176634×10⁻¹⁹ C exactly (SI defining constant).

How to use

1

Choose direction and charge unit

Pick eV → V or V → eV, then elementary-charge units (e) or coulombs (C).

2

Enter energy (or voltage) and charge magnitude

For a single electron or proton use Q = 1 e, or Q = 1.602176634×10⁻¹⁹ C. Charge is a magnitude; sign is not modeled.

3

Read volts or eV

The result updates as you type. Very small coulomb-mode values show in scientific notation. Charge must be non-zero when solving for voltage.

Example calculations

Common configurations with formula and result.

ϟ

Single electron

1 eV · Q = 1 e

1 ÷ 1
1 V
ϟ

Multiple elementary charges

25 eV · Q = 10 e

25 ÷ 10
2.5 V
ϟ

Coulomb charge

25 eV · Q = 10 C

1.602176634×10⁻¹⁹ × 25 ÷ 10
4.005441585×10⁻¹⁹ V
ϟ

Megaelectronvolt scale

1 MeV = 10⁶ eV · Q = 1 e

1000000 ÷ 1
1,000,000 V
ϟ

Volts → eV (elementary)

2.5 V · Q = 10 e

2.5 × 10
25 eV

Quick eV → V examples (Q = 1 e)

Common values at a glance.

EnergyChargeVoltage
1 eV1 e1 V
10 eV1 e10 V
1 eV2 e0.5 V
1 keV1 e1,000 V
1 MeV1 e1,000,000 V
25 eV10 e2.5 V
i With Q = 1 e, volts equal the numeric eV value. Double the charge halves the voltage for the same energy. Q is charge magnitude.

eV to Volts calculator specification

Version 1.3.0 · Engine tested

Calculation status

Review policy · Evidence

Definition
An electronvolt (eV) is the kinetic energy gained by one elementary charge when accelerated through one volt. Voltage follows the electrostatic relation ΔE = qΔV. With charge in elementary-charge units, V = E(eV) / Q(e). With coulombs, V = E(eV) × e / Q(C) using the exact SI value e = 1.602176634×10⁻¹⁹ C. This tool relates eV ↔ V for both charge units. It reports potential-difference magnitude; electron vs proton sign is not modeled.
What it calculates
Magnitude of the equivalent potential difference from electron-volt energy and charge (elementary-charge units or coulombs), or energy in eV from volts and charge.
Inputs
  • Energy E (eV) or voltage V (V)
  • Charge magnitude Q in elementary-charge units (e) or coulombs (C)
Outputs
  • Voltage in volts (energy→voltage modes)
  • Energy in electron-volts (voltage→energy modes)
Formula
V=E(eV)/Q(e); V=e·E(eV)/Q(C); E=V·Q(e); E=V·Q(C)/e
Assumptions
  • Elementary charge e = 1.602176634×10⁻¹⁹ C exactly (SI defining constant; no uncertainty)
  • Uses the electrostatic energy–potential relation E = qV
  • Q(e) and Q(C) denote charge magnitude; sign and direction of the potential difference are not modeled
Units
  • eV, e or C → V
Boundary conditions
  • eV→V: Q = 0 → ZERO_CHARGE (hard). V = E/Q is undefined, including 0/0
  • Charge magnitude must be ≥ 0 (VALUE_MUST_BE_NON_NEGATIVE)
  • Zero energy with Q ≠ 0 → 0 V
  • V→eV: zero V or Q → 0 eV (product is defined)
  • Coulomb path uses exact e = 1.602176634×10⁻¹⁹ C
Example
25 eV ÷ 10 e = 2.5 V
Validation cases

15 published on this page · 21/21 tests · Production surface contract 3/3 · View evidence

  • 1 eV, Q = 1 e → 1 V
  • 25 eV, Q = 10 e → 2.5 V
  • 1 MeV, Q = 1 e → 1,000,000 V
  • 2.5 V, Q = 10 e → eV → 25 eV
  • 25 eV, Q = 10 C → 4.005441585×10⁻¹⁹ V
  • 50 eV, Q = 10 e (2× E) → 5 V (linear in E)
  • 25 eV, Q = 5 e (half Q) → 5 V (inverse in Q)
  • 25 eV, Q = 0 e → ZERO_CHARGE (hard: Q ≠ 0 when solving for V)
  • 0 eV, Q = 0 e → ZERO_CHARGE (0/0 undefined)
  • 0 eV, Q = 10 e → 0 V
  • 0 V, Q = 10 e → eV → 0 eV
  • 0 V, Q = 0 e → eV → 0 eV
  • 1 V, Q = 1.602176634×10⁻¹⁹ C → eV → 1 eV
  • 1 eV, Q = 1 e and 1 eV, Q = 1.602176634×10⁻¹⁹ C → both 1 V (unit-cross equivalence)
  • 25 eV → 2.5 V → eV round-trip at Q = 10 e → 25 eV
Sources
  • BIPM SI Brochure, 9th edition — SI defining constants — elementary charge e = 1.602176634×10⁻¹⁹ C exactly
    Supports: Exact SI elementary charge; coulomb-mode scale; 1 eV = e J
  • BIPM SI base unit — ampere — The ampere is defined by taking the fixed numerical value of the elementary charge e
    Supports: e is an SI defining constant with no uncertainty
  • NIST Guide to the SI (SP 811) — Electronvolt as a non-SI energy unit accepted for use with SI
    Supports: eV is energy; volts remain SI potential; eV ↔ J via e
Calculation version
1.3.0

Background

Interpretation and common distinctions.

Relate electronvolt (eV) energy to electric potential difference (V) through ΔE = qΔV. Electronvolts and volts measure different physical quantities; charge is required to connect them.

Modes

Tab Formula Typical use
eV → V (e) V = E((eV)) / Q((e)) Particles, beam energy, single electrons
eV → V (C) V = 1.602176634×10⁻¹⁹ × E((eV)) / Q((C)) Charge given in coulombs
V → eV (e) E((eV)) = V × Q((e)) Energy from accelerating voltage
V → eV (C) E((eV)) = V × Q((C)) / e Same, with Q in coulombs

Charge inputs are magnitudes (|Q|/e or |Q| in C). Electron charge is −e and proton charge is +e; this page does not assign a sign to the potential difference.

What is an electronvolt?

One electronvolt is the energy required to move one elementary charge through a potential difference of one volt:

1 eV = 1 V × 1 e = 1.602176634×10⁻¹⁹ J

(exactly, because e is an SI defining constant). So for Q = 1 e, the numeric value of energy in eV equals the accelerating voltage in volts. For other charge magnitudes, always divide (or multiply) by Q.

Related SI energy conversions (not voltage) include keV, MeV, joules, and watt-hours — useful when you only need energy-unit conversion rather than potential.

Constant used

Symbol Value Status Authority
e 1.602176634×10⁻¹⁹ C Exact SI defining constant BIPM SI Brochure, 9th edition

Agent / API notes

Capability id: electrical.ev_voltage · tool id: ev-to-volts · engine ev-voltage · pin 1.3.0.

Canonical fields: mode (or direction + charge_unit), energy_eV / voltage_V, charge_value. Share-URL aliases a / b remain valid. Charge convention is magnitude. Solving for voltage with Q = 0 returns ZERO_CHARGE.

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Frequently asked questions

Key distinctions behind the calculation.

How do I convert eV to volts?

Divide energy in electron-volts by the charge magnitude. With elementary-charge units: V = E(eV) / Q(e). With coulombs: V = 1.602176634×10⁻¹⁹ × E(eV) / Q(C). There is no unconditional 1 eV = ? V conversion — eV is energy and volts are potential.

What is an electronvolt (eV)?

An electronvolt is a unit of energy: the energy gained by one elementary charge accelerated through a potential difference of one volt. 1 eV = 1.602176634×10⁻¹⁹ joules exactly, because e is an exact SI defining constant.

Why isn't eV the same as volts?

Volts measure electric potential (energy per charge). Electronvolts measure energy. You need the charge amount to relate them: ΔE = qΔV. The page title is a search name, not a pure unit conversion.

Is charge signed (electron vs proton)?

This calculator reports the magnitude of the equivalent potential difference. Elementary charge e is the positive SI constant. Electron charge is −e and proton charge is +e; signed electrostatic potential changes depend on direction and sign convention, which are not modeled here. Enter |Q|/e (use 1 for a single electron or proton).

When should I use elementary charge vs coulombs?

Use elementary-charge units (e) for particles and atomic-scale problems — Q is usually 1, 2, …. Use coulombs for macroscopic charge. One elementary charge is exactly 1.602176634×10⁻¹⁹ C.

Why is the coulomb result so small?

One eV is only 1.602176634×10⁻¹⁹ J. Dividing by a charge of several coulombs yields a tiny voltage. That is expected; try Q = 1.602176634×10⁻¹⁹ C for a single-elementary-charge case.

How do I convert volts back to eV?

Multiply voltage by charge magnitude: E(eV) = V × Q(e), or E(eV) = V × Q(C) / 1.602176634×10⁻¹⁹.

What happens if charge is zero?

When solving for voltage, Q = 0 is invalid. V = E/Q is undefined (including 0/0). The API returns HTTP 400 with code ZERO_CHARGE. Reverse energy E = V × Q is 0 eV if V or Q is 0.

Can I convert eV to joules or kWh instead?

Yes for energy units — 1 eV = 1.602176634×10⁻¹⁹ J exactly. That is a pure energy conversion. This page relates eV to volts via charge, not to joules alone.