Australians lose more than USD 100 million worth of coins down the back of sofas and car seats each year, the Royal Australian Mint said.
Mint chief executive Ross MacDiarmid told a government hearing that 255 million coins disappear annually and are replaced.
"Most of the coins that we provide are against coins that disappear down the back of chairs, down the back of car seats, into rubbish dumps and, in some cases, are taken overseas," he told a Senate committee Tuesday night.
"We are talking about USD 102 million worth of coins."
MacDiarmid said some of the coins the Mint replaced each year were those "sitting in people's drawers for long periods of time or in jars".
The coin manufacturer was not able to reveal how much it costs to produce the 255 million pieces each year.
There are about five billion coins - made from copper and nickel and stamped with images of the native echidna or spiny anteater - in circulation in Australia.
The government is considering whether the Mint, in Canberra, should be one of several publicly owned assets sold under the conservative administration's plans to cut back spending.
The Senate hearing was told the Mint was proposing a review of Australia's coin array amid a decline in their use as people increasingly turn to debit and credit cards for payments.
MacDiarmid said the review could also look into whether the small five cent coin, which cost six cents to produce, should be scrapped.