There are 10 myki cards in circulation for every weekday public transport user, with the massive over subscription blamed on a lack of short-term tickets.

Public Transport Users Association president Tony Morton said the ticketing authority would be making millions from the surplus cards.

"The government is not so concerned about having millions and millions of cards because at $3 or $6 each it is about $30 million worth of revenue," he said.

There are 10 million myki cards in circulation, almost double Victoria's population of 5.8 million.

Dr Morton said the surplus in cards was a predictable problem caused by the lack of a short-term ticket.