Len Brown is well ahead in the race to become the first mayor of the Auckland super city.

A HorizonPoll survey published online this morning shows he's won the votes of almost half of those who've already sent back their ballot papers.

John Banks trails with only 22 per cent. So far though, only about a quarter of people say they've completed their voting paper. Of those yet to vote, 36 per cent say they go for Len Brown and 21 per cent for John Banks.

Meanwhile, in another Horizon poll, the majority of those who haven't yet voted don't know when the deadline is. 51 per cent of the 570 people asked said they didn't know voting closes at 12 noon on Saturday 9th October, and votes needed to be posted before 5pm on Wednesday 6th October.

Also, 82 per cent also didn't realise voting papers could be returned to any of Auckland's public libraries on election day.