The unit of electric charge in the electromagnetic centimeter-gram-second system, where one abcoulomb is equal to 10 coulombs.

In the electromagnetic cgs system, electrical current is a fundamental quantity defined via Ampère's law and takes the permeability as a dimensionless quantity (relative permeability) whose value in a vacuum is unity and, as a consequence, the square of the speed of light appears explicitly in some of the equations interrelating quantities in this system.