For other uses see Erg (disambiguation)

An erg is the unit of energy and mechanical work in the centimetre-gram-second (CGS) system of units, symbol "erg". Its name is derived from the Greek word meaning "work".

The erg is a quite small unit, equal to one a force of one dyne exerted for a distance of one centimetre. In the cgs base units , it is equal to one gram-square centimetre per second squared (g·cm²/s²). It is thus equal to 1 × 10^-7 joules or 0.1 microjoule (µJ) in SI units.