Voltage Converter – Convert Between nV, mV, V, kV, MV, and GV
The Voltage Converter is a free online tool that instantly converts electric potential values between seven SI-prefixed units — from nanovolts to gigavolts. Whether you are an electronics engineer converting sensor output from millivolts to volts, a student comparing transmission-line kilovolts to household mains voltage, or a technician working with thermocouple readings in the millivolt range, this tool delivers accurate results in real time with configurable decimal precision.
All conversions normalize through the Volt (V) as the canonical base unit. Every cross-unit conversion follows the formula:
result = inputValue × (fromUnitFactor / toUnitFactor)
Because all supported units are exact powers of ten, conversions are mathematically precise within the limits of IEEE 754 double-precision arithmetic. For very large or very small values the tool automatically switches to scientific notation so results remain readable.
Supported Voltage Units
The converter covers the full practical range of SI voltage prefixes used in modern electronics, power engineering, and scientific instrumentation.
- Nanovolt (nV) — 10⁻⁹ V — Used in precision sensor measurement, superconducting quantum interference devices (SQUIDs), and low-noise amplifier characterisation. Biomedical research instruments routinely operate at nanovolt sensitivity.
- Microvolt (µV) — 10⁻⁶ V — Typical for biomedical signals such as electroencephalogram (EEG) brain waves (10–100 µV) and electrocardiogram (ECG) signals (0.5–5 mV). Also common in strain gauge and piezoelectric sensor outputs.
- Millivolt (mV) — 10⁻³ V — The standard measurement range for thermocouples (1–100 mV), battery cell terminal voltages during charge/discharge testing, and audio line-level signals (−10 dBV ≈ 316 mV).
- Volt (V) — base unit — The SI unit of electric potential difference and electromotive force, defined via the elementary charge and the Joule. All other units in this converter are expressed as multiples of the Volt.
- Kilovolt (kV) — 10³ V — Used in power distribution substations, medical X-ray tube voltage (40–150 kV), cathode-ray tubes, and high-voltage laboratory testing. Grid transmission lines operate at 66 kV, 132 kV, or 400 kV depending on the country.
- Megavolt (MV) — 10⁶ V — Found in lightning discharge channels (estimated 100–300 MV), Van de Graaff generators used in nuclear physics experiments, and some pulsed-power research facilities.
- Gigavolt (GV) — 10⁹ V — A theoretical-scale unit encountered in extreme plasma physics, cosmic-ray energy calculations, and particle physics literature. Not a unit used in everyday electrical engineering.
Conversion Examples
The following examples illustrate common conversions across the supported range:
- 1 V → mV: 1 × (1 / 10⁻³) =
1,000 mV - 120 V → kV: 120 × (1 / 10³) =
0.12 kV(US mains) - 400 kV → V: 400,000 × 1 =
400,000 V(HV line) - 5 V → µV: 5 × (1 / 10⁻⁶) =
5,000,000 µV(USB power) - 50 mV → nV: 0.05 × (1 / 10⁻⁹) =
50,000,000 nV
Key Features
- Instant conversion — results update automatically as you type, with no button press required.
- Swap units — reverse the From/To direction in one click and immediately see the opposite conversion.
- Show all units — toggle on a complete reference table showing the input value in every supported unit simultaneously.
- Real-world context — for recognised voltage levels (AA battery, USB, car battery, mains, transmission line) the tool displays a brief contextual note explaining the real-world application.
- Adjustable precision — set decimal places from 0 to 10; the tool automatically uses scientific notation for extreme values.
- Negative values supported — polarity-reversed potentials convert correctly across all units.
Voltage in Electrical Engineering and Physics
Voltage — formally electric potential difference — is the work done per unit charge when moving a positive test charge between two points in an electric field. It is defined as V = W / Q, where W is energy in Joules and Q is charge in Coulombs. The unit is named after Alessandro Volta, who invented the first electrochemical cell in 1799.
In circuit analysis, voltage is the driving quantity for current flow: Ohm's law states that V = I × R, relating voltage across a resistor to the current through it and its resistance. Power dissipated in a resistive load is P = V × I, linking voltage directly to the energy and power converters in this suite of tools.
SI prefixes make it practical to express voltages across an enormous dynamic range — from the nanovolt thermal noise floor of low-noise amplifiers at room temperature (about 1 nV/√Hz for a 50 Ω source) to the hundreds of kilovolts used in national electricity grids, spanning over fifteen orders of magnitude.