⚡ Energy Density of Fields Calculator
Calculate the energy stored per unit volume in an electric field or a magnetic field.
V/m or T
What field energy density is
Electric and magnetic fields store energy in the space they occupy. This calculator computes the energy per unit volume (energy density) for a uniform electric or magnetic field.
The formulas
For an electric field, energy density u = ½ε0E², where ε0 is the permittivity of free space and E is the electric field strength in volts per meter. For a magnetic field, u = B² / (2μ0), where μ0 is the permeability of free space and B is magnetic flux density in tesla.
These are standard formulas from classical electromagnetism, valid for fields in a vacuum or air.
Last reviewed August 2026