About 240,000 voters are on the electoral role and ACT Electoral Commissioner Phil Green said Canberrans could expect the result two to five days earlier than usual.

After the last election, 40 data-entry operators took 10 days to input 180,000 votes twice. ''The scanners will be able to scan 240,000 votes in one or two days,'' Mr Green said.

Postal votes are accepted until October 24. Mr Green said the results could be available as early as October 25.

The scanners will read the ballots in batches of 50 and any unclear votes will be cross-checked against the originals.

In the 2004 election, 28,169 votes were recorded electronically. This year Mr Green is expecting 30,000.

Twenty machines at five pre-polling stations in Belconnen, Gungahlin, Civic, Woden and Tuggeranong will record electronic votes from September 29.

''Last time we put all the pre-polling votes on to the website at 10 [minutes] past six on election night.''

Mr Green said 16 of the 17 winning candidates were correctly identified.

There will be no electronic voting on polling day.

Almost 94 per cent of those on the electoral roll voted four years ago. There were 40 multiple votes. Mr Green said only five were unexplained. ''It's usually human error, marking off the person below or above in the roll,'' he said.

Members of the Legislative Assembly are elected using a proportional representative system known as Hare-Clark.

There are 17 places up for grabs, with five members from the Brindabella and Ginninderra electorates and seven members from Molonglo.

To be elected, a candidate needs to receive a quota of votes. Each voter has a single vote, which can be transferred from candidate to candidate according to their preferences, until all the vacancies are filled.

The ACT and Tasmania use a system known as Robson rotation to make positions on the ballot paper more equal.

There are 420 versions of the Molonglo ballot and 60 versions of the Brindabella and Ginninderra ballot papers to allow each candidate a turn in every position within their party's column. Mr Green said Robson rotation reduced the artificial concentration of votes on a No1 candidate and reflected voters' choices of other candidates within their preferred party.

The ballot paper order will be drawn on September 25.

Canberrans have until September 19 to update their details with the Electoral Commission.