Electric Field Strength Converter
Convert electric field strength between volt per meter, kilovolt per meter, kilovolt and volt per centimeter and inch, volt per mil, newton per coulomb and the CGS units. Pick two units, enter a value and read the result instantly.
Select two units to see the conversion factor.
Electric field strength is voltage per length (V/m). It is not electric potential or voltage (V), and not magnetic field strength (A/m).
Electric Field Strength Formula
Electric field strength is the force per unit charge, which equals the potential change per unit distance: E = F ÷ q = V ÷ d in a uniform field, measured in V/m. Every unit is a fixed multiple of V/m. Result = value × (source factor ÷ target factor). Exact building blocks: 1 N/C = 1 V/m, 1 kV = 1,000 V, 1 cm = 0.01 m, 1 in = 0.0254 m, 1 mil = 0.0000254 m, 1 abvolt = 10⁻⁸ V and 1 statvolt = 299.792458 V.
What Is Electric Field Strength?
Electric field strength, written E, tells you how strong the electric force is at a point in space. It is defined as the force a small positive test charge would feel per unit of its charge, E = F ÷ q, so its natural unit is the newton per coulomb (N/C). It is also the rate at which electric potential changes with distance, and that gives the equivalent SI unit, the volt per meter (V/m). The two are exactly the same: 1 N/C = 1 V/m.
In a uniform field between two parallel plates, the field strength is simply the voltage across them divided by the gap: 5,000 V across 2 mm gives 5,000 ÷ 0.002 = 2.5 × 10⁶ V/m. The fair-weather field near the ground is about 100 V/m, dry air breaks down and sparks at around 3 × 10⁶ V/m (30 kV/cm), and the insulation in high-voltage equipment is rated in the same units. Typical insulating oils, polymers and films are specified in kV/mm or, in North America, in volts per mil.
The units differ only in how they split voltage and length. Per centimeter and per inch are common on datasheets and breakdown charts; the volt per mil (a mil is a thousandth of an inch) is standard for film and wire-insulation ratings. The statvolt per centimeter and abvolt per centimeter are the Gaussian and electromagnetic CGS units.
Do not confuse field strength with potential. Electric potential (voltage, V) is the energy per charge at a point or between two points (Electric Potential Converter); the field strength is its gradient. A 1,000 V battery can create a weak field across a wide gap and a huge one across a tiny gap. Electric field strength is also a different quantity from magnetic field strength in A/m (Magnetic Field Strength Converter).
Supported Units
This converter supports the following 13 electric field strength units. The last column gives the value of each unit in the base unit, V/m. The newton per coulomb equals the volt per meter exactly.
| Unit | Symbol | Value in V/m |
|---|---|---|
| Volt per meter | V/m | 1 |
| Kilovolt per meter | kV/m | 1,000 |
| Kilovolt per centimeter | kV/cm | 100,000 |
| Volt per centimeter | V/cm | 100 |
| Millivolt per meter | mV/m | 0.001 |
| Microvolt per meter | µV/m | 1e-6 |
| Kilovolt per inch | kV/in | 39,370.07874 |
| Volt per inch | V/in | 39.37007874 |
| Volt per mil | V/mil | 39,370.07874 |
| Abvolt per centimeter | abV/cm | 1e-6 |
| Statvolt per centimeter | statV/cm | 29,979.2458 |
| Statvolt per inch | statV/in | 11,802.85268 |
| Newton per coulomb | N/C | 1 |
How to Use the Electric Field Strength Converter
- Type the electric field strength in the value box. Decimals and scientific notation such as 0.0025 or 2.5e-3 are accepted.
- Choose the From unit and the To unit.
- The result appears instantly, or press Convert Now. Very large or very small results are shown in scientific notation.
- Use Swap Units to reverse the conversion, Copy Result to copy the answer, open Show this value in all units for a full list, and Clear to start again.
Step-by-step by hand
- Find the size of each unit in the common base unit (V/m): 1 kV/cm = 100,000 V/m and 1 V/m = 1 V/m.
- Divide the source size by the target size to get the conversion factor: 100,000 ÷ 1 = 100,000, so 1 kV/cm = 100,000 V/m.
- Multiply by your value: 30 kV/cm × 100,000 = 3,000,000 V/m.
Field strength is a vector, and its sign only shows direction along an axis, so a minus sign is accepted. Zero is also valid.
Common Electric Field Strength Conversions
- Breakdown of dry air: about 30 kV/cm equals 3,000,000 V/m and 3,000 kV/m.
- Film rating: 1,000 V/mil equals 39,370,078.74 V/m and 393.7007874 kV/cm.
- Newton per coulomb: 250 N/C equals 250 V/m.
- Per inch to per meter: 100 V/in equals 3,937.007874 V/m.
- Weak fields: 5 mV/m equals 5,000 µV/m, a level seen in radio field-strength measurements.
- CGS to SI: 1 statvolt/cm equals 29,979.2458 V/m, and 1 abvolt/cm equals 1e-6 V/m.
V/m to Other Electric Field Strength Units
Quick reference for frequently used values
| V/m | kV/m | V/cm | kV/cm | V/mil |
|---|---|---|---|---|
| 1 | 0.001 | 0.01 | 1e-5 | 2.54e-5 |
| 100 | 0.1 | 1 | 0.001 | 0.00254 |
| 1,000 | 1 | 10 | 0.01 | 0.0254 |
| 10,000 | 10 | 100 | 0.1 | 0.254 |
| 100,000 | 100 | 1,000 | 1 | 2.54 |
| 1,000,000 | 1,000 | 10,000 | 10 | 25.4 |
| 3,000,000 | 3,000 | 30,000 | 30 | 76.2 |
Where and Why This Conversion Is Used
- High-voltage engineering: sizing gaps and insulation so the field stays below breakdown.
- Dielectric and insulation testing: film, cable and oil ratings in kV/mm, V/mil or kV/cm.
- EMC and radio: field-strength limits and measurements in V/m and µV/m.
- Electrostatics and semiconductors: fields in gate oxides, junctions and electrostatic precipitators.
- Physics education: moving between N/C, V/m and the CGS statvolt per centimeter.
Limitations
- E = V ÷ d only holds for a uniform field. Sharp points and edges concentrate the field far above the average.
- Breakdown strength varies with gas, pressure, humidity, electrode shape and the duration of the voltage, so a figure for one case does not transfer to another.
Important Differences Between Related Electrical Measurements
- Electric field strength, V/m is voltage per length. Electric potential, V is the voltage itself. The same 1,000 V is a field of 1 kV/m across a meter and 1 MV/m across a millimeter.
- Field strength vs force: the field is force per charge (N/C). The actual force on a charge q is F = q × E, measured in newtons.
- Electric vs magnetic field strength: E is in V/m and acts on any charge. H is in A/m and is produced by moving charge. They are different fields with different units, linked only through electromagnetic waves.
- Field strength vs flux density: the electric flux density D, in C/m², equals ε × E and also depends on the material. It is a different quantity from E.
Each converter on this site changes units within one quantity only, and none of them mixes quantities. The related tools are: Charge, Current, Linear Charge Density, Surface Charge Density, Volume Charge Density, Linear Current Density, Surface Current Density, Electric Field Strength, Electric Potential, Electric Resistance, Electric Resistivity, Electric Conductance, Electric Conductivity, Electrostatic Capacitance and Inductance.