The erg is a unit of energy equal to 10−7 joules (100 nJ). It originated in the centimetre–gram–second (CGS) system of units. It has the symbol erg. The erg is not an SI unit. Its name is derived from ergon (ἔργον), a Greek word meaning 'work' or 'task'.An erg is the amount of work done by a force of one dyne exerted for a distance of one centimetre. In the CGS base units, it is equal to one gram centimetre-squared per second-squared (g⋅cm2/s2). It is thus equal to 10−7 joules or 100 nanojoules (nJ) in SI units. An erg is approximately the amount of work done (or energy consumed) by one common house fly performing one "push up", the leg-bending dip that brings its mouth to the surface on which it stands and back up.
1 erg = 10−7 J = 100 nJ
1 erg = 10−10 sn⋅m = 100 psn⋅m = 100 picosthène-metres
1 erg = 624.15 GeV = 6.2415×1011 eV
1 erg = 1 dyn⋅cm = 1 g⋅cm2/s2