Electric charge is the difference in unit expressed in number of electrons as compared to protons. The electron carries a negative charge while the proton carries a positive charge. If there are more electrons than protons, the atom has a negative charge. On the other hand, if there are more protons than electrons, the atom has a positive charge. SI unit of charge is the coulomb (C). Our online charge converter Tool will convert a charge in 15+ units in just one click.