QUEENSLAND and New South Wales account for more than half of the 1.5 million Australian voters who are not enrolled to vote, the Australian Electoral Commission has revealed.
The AEC on Tuesday launched its Count Me In campaign in a bid to prompt Australians to vote and update their details.
In Queensland and NSW, 864,800 people are missing from electoral rolls - 389,900 in the sunshine state and 475,800 south of the border.
That equates to an average of 13,000 missing voters per electorate in Queensland and 9900 in NSW.
Electoral Commissioner Ed Killesteyn said the number of eligible people not enrolled to vote was "not good for the health of our democracy".
"It's been compulsory to enrol to vote for 100 years and it's part of our democratic fabric, but the estimated number of missing voters is serious and comparable to a city the size of Perth or most of Brisbane disappearing off the map," Mr Killesteyn said.
From Tuesday the AEC began sending a postcard to every Australian household outlining the three steps to enrol or update enrolment details.
"The AEC is reaching out to all households because the 1.5 million missing voters is a very large group that is widely distributed throughout the community," Mr Killesteyn said.
"While our data tells us that only one in two 18-19 year olds are on the electoral roll, the issue is not confined just to youth, but ranges across a wider 18-39 age group. Some Australians may not have enrolled to vote for one or two or more elections."
Mr Killesteyn said another substantial category of missing voters were those who failed to update their address details after moving house, and later drop off the electoral roll.
All Australian citizens aged 18 years and over must enrol to vote. Australians aged 16 and 17 can enrol now and vote when they turn 18.
To check if you're enrolled to vote visit aec.gov.au/check or call 132 326.
The estimated number of eligible Australian voters missing from the electoral roll by state and territory, and a statistical average of missing per federal electorate in each state or territory: