On any given day 400 young people, some as young as 10, are locked up in detention in New South Wales - and half of them are there because they have been refused bail.
But only a third of those on remand were ultimately sentenced to time in a detention centre.
The figures are contained in a new report, by the Australian Institute of Health and Welfare (AIHW), released today. It says NSW has the highest proportion of juveniles under court-ordered supervision who are detained (20 per cent), rather than supervised in the community, even though by law detention is meant to be used only as a "last resort".
The NSW state government is currently reviewing laws dealing with young offenders, as well as bail laws.
For many juveniles in detention - whether they have been sentenced or were on remand - it was not the first time, and the report shows that for more than 40 per cent of juveniles sentenced to detention nationwide in 2010/11, it was not their first time. More than 80 per cent had already been sentenced to a community-based sentence under supervision.
A Sydney Morning Herald series in April highlighted the problem of high offending rates among juveniles, and many experts called for earlier intervention to steer young people away from the courts and detention centres.
A spokesman for Mission Australia said their youth crime prevention program had shown early success and produced better, and cheaper, results than detention.
Nearly half of the young people in detention in NSW on any given day are Aborigines, who are 23 times more likely to be in a juvenile detention centre than non-indigenous young people - however, this over-representation has been dropping slightly in recent years.
Young people in NSW spent about 60 days in detention, on average, slightly below the national average.
A spokesman for the AIHW, Tim Beard, said overall, few young Australians were involved in the juvenile justice system.
"Figures showed police had taken action against about three per cent of those aged 10-17, and those in detention represented fewer than 0.3 per cent of that age range," he said.