The pile of "lost" superannuation has risen to $18.1 billion, up from $17.4 billion a year ago.
The latest Westpac Lost Super Report, researched by Core Data, estimates half the population with superannuation funds is likely to have lost some super.
"We are all planning to retire, so why don't more of us spend just a few minutes to find any lost super?" Westpac head of superannuation Deanne Stewart said.
For NSW and Victoria, the average estimated lost amount per person with super is about $2500.
Super money is deemed "lost" when funds do not have the contact details of the member and the fund has been inactive for a specified minimum period.
Multiple super accounts - where a person has several accounts with different funds - is one of the main reasons people fail to keep track of their super. The report estimates that almost a third of Australians with superannuation have more than one super account.
Multiple accounts are more likely with those who change jobs often, especially those working in retail and hospitality where part-time and casual employment is common.
The government has long recognised the problem of lost super and has introduced several reforms to help reunite the money with its owners.
Next year, superannuation funds will start automatic consolidation of some accounts of their members. The Tax Office and super funds are making increasing use of tax file numbers to make owners aware of their lost super.
Also, super funds must transfer money from accounts to the Tax Office if the accounts have been inactive, the owner cannot be contacted, and where there is less than $2000 in the account. Interest is paid on the super account at a rate equal to inflation while the Tax Office uses its data-matching capabilities to locate the owners.
Locating lost super is easy. You can check for lost super by visiting ato.gov.au/superseeker or by calling 13 28 65.