The SI unit of electric current density is ampere per square meter. The standard unit for current density is amperes per m 2 (amps/m 2). The unit of electric current density is denoted as ampere per square meter. It concerns the amount of current flowing across the given area. The SI unit of current density is Ampere/metre2. This unit also helps you remember the formula for calculation of such a density. It is a vector quantity. It is the current flow divided by the area of the cross section. Since Ampere is the unit of current and metre2 is the unit for measuring cross-sectional area, one can easily derive that the formula for current density. In the study of electromagnetism , Current Density is the measurement of electric current. What's the current density formula? amount of electric current travelling per unit cross-section area The symbol "J" is used for electric current density. To calculate current density you divide current by the area. Current density or electric current density is related to electromagnetism and is defined as the amount of electric current flowing through a unit cross-sectional area.