Greek coins have various name accoding to the weight. The standard coins are Drachm and Obol (1/6 Drachm), and there are some units, multiple of the standard. However, the weight of the standard is differed from the city. Following is a standard of Attic coinage.
Dekadrachm =10 drachms 43g
Tetradrachm =4 drachms 17.2g
Didrachm(Stater) =2 drachms 8.6g
Drachm =6 obols 4.3g
Tetrobol =4 obols 2.85g
Triobol =3 obols 2.15g
Diobol =2 obols 1.43g
Trihemiobol =1 1/2 obols 1.07g
Obol =1/6 drachm 0.72g
Tritartemorion =3/4 obol 0.54g
Hemiobol =1/2 obol 0.36g
Trihemitartemorion =3/8 obol 0.27g
Tetartemorion =1/4 obol 0.18g
Hemitartemorion =1/8 obol 0.09g

Its principal unit is called "stater" and in Attic standard, it was Didrachm weighing 8.6g, though it was changed to Tetradrachm weighing17.2g. This standard was also adopted not only in some cities of Sicily, northern part of Aegean islands, but also in Macedonian kingdom since the reign of Alexander the Grate.

Corinthian Stater was also 8.6g, though it was not Didrachm, but Tridrachm, so the drachm weighing 2.9g. This standard was adopted in the cities of north-west Greece, many colonies in Italy and Sicily.

Aigina, who introduced the coinage earlier than any other Greek mainland cities, had also her own standard. The stater was Didrachm weighing12.6g so the drachm was 6.3g. This standard was adopted in the cities of Peloponnese, central Greece, Cyclades islands, Crete and Southern part of Asia Minor.

Some Euboean cities also had another standard. The stater was Tridrachm of16.8g and the standard was adopted in Euboean colonies in northern Aegean islands and Sicily.

Sicily after the middle of 5th century produced many bronze coins and the standard was differed from the silver coins, which had same standard as Greek cities. The standard is called "Litra" and though the weight was differed from the cities, Litra was always divided into 12 "Onkiai". Other than these unit, there were Hemilitron (=6 Onkiai), Pentonkion (=5 Onkiai), Tetras (=4 Onkiai), Trias (=3 Onkiai) and Hexas (=2 Onkiai).


  Fred S. Kleiner, "Greek and Roman Coins in the Athenian Agora " (1975)
John H. Kroll and Alan S. Walker , "The Greek Coins (Athenian Agora, Vol. 26)" (1993)
Thomas J. Figueira , "The Power of Money: Coinage and Politics in the Athenian Empire " (1998)
Kirsty Shipton and Andrew Meadows (eds.), "Money and Its Uses in the Ancient Greek World " (2002)