Sportsbet will lose at least $5.2 million thanks to its decision to pay out early on Bill Shorten winning Saturday's federal election as large bookmakers again had to admit they had misread the political landscape.

The betting company paid out on Mr Shorten becoming prime minister two days before Australians went to the polls, where voters surprisingly chose to re-elect Scott Morrison's Coalition government. Sportsbet said on Thursday Mr Shorten was at Winx-like odds of $1.16 to win.

"We paid out $1.3 million early to punters who backed Labor early, but on top of that we obviously have a massive payout on the Coalition which will be at least three times that figure," Sportsbet spokesman Richard Hummerston told The Age and SMH.

"Seventy per cent of the cash staked before the early payout had come for Labor, our punters had called the election early. We thought we’d simply give them their cash early."