Electric Field Calculator
Enter the voltage across two parallel plates and the gap between them to get the uniform electric field strength in volts per metre.
Field strength in one step
The electric field calculator divides the voltage by the plate separation to return the uniform field strength E in volts per metre (V/m).
Use SI units
Voltage in volts and the gap in metres give the field in V/m — convert millimetres to metres (divide by 1000) before you enter the distance.
What is the electric field?
Force per unit charge
The electric field calculator finds the strength of the uniform field between two parallel plates — the region where a charge feels a steady push. An electric field describes the force a unit positive charge would feel at a point in space, and between flat parallel plates held at a fixed voltage that field is the same everywhere. Feed in the voltage across the plates in volts and the distance between them in metres, and the tool returns the field strength in volts per metre (V/m), the number behind capacitors, oscilloscope deflection plates, and the dielectric limits of insulators.
Enter a voltage in volts and a plate separation in metres to get the uniform electric field strength in volts per metre instantly.
For a uniform field between parallel plates, the field strength is simply the voltage divided by the distance between the plates.
E = V / dThe closer the plates, the stronger the field for the same voltage: halve the gap and you double the field strength. Use volts for the voltage and metres for the distance and the field comes back in volts per metre (V/m), which is the same unit as newtons per coulomb (N/C).
Suppose 12 V is applied across two plates separated by 0.01 m (1 cm).
Take the voltage
V = 12 V — the potential difference across the plates.
Divide by the gap
12 / 0.01 = 1200 — voltage divided by the separation in metres.
Read the field
E = 1200 V/m — the uniform electric field a charge feels between the plates.
The formula is exact for an ideal uniform field, but a couple of practical points are worth keeping in mind.
Uniform fields only, and consistent units
E = V / d holds for the uniform field between flat, parallel plates and ignores fringing at the edges. It does not describe the field around a point charge or a curved conductor, which falls off with distance. Keep your units consistent — volts for voltage and metres for the gap — or the result will be wrong: convert centimetres or millimetres to metres before you enter the distance.