The dupondius (Latin two-pounder) was a bronze coin used during the Roman Empire and Roman Republic valued at 2 asses (1/2 of a sestertius or 1/8 of a denarius).

It was introduced during the Roman Republic as a large cast coin, although even at introduction it weighed less than 2 pounds. The coin featured the bust of Roma on the obverse and a six-spoked wheel on the reverse. The type was not produced much during the Republic. With the coinage reform of Augustus in 23 BC, the sestertius and dupondius were produced in a golden alloy of bronze called orichalcum by numismatists, while lower denominations were produced out of reddish copper. The dupondius was further distinguished from the similarly sized as with the addition of a radiate crown to the bust of the emperor in 66 AD during the time of Nero. Using a radiate crown to indicate double value was also used on the antoninianus (double denarius) and double sestertius . The dupondius was manufactured until the late 3rd century AD.

Since dupondii from the time of Nero and before lack the radiate crown, it is often hard to distinguish between the as and the dupondius due to heavy patination which obscures coin's original color.

See also: Roman currency.