Sydney's population has passed the 4.5 million mark for the first time, with the inner-west area of Canada Bay the fastest-growing area, the Sydney Morning Herald reported today.

That means there are more people in Sydney than the entire population of New Zealand, which is 4,268,000.

The population of Australia's largest city increased by 85,400 in the year to June 30 last year, according to figures from the Australian Bureau of Statistics.

Despite the strong growth across Sydney, which averaged 1.9 per cent, it still fell behind other capital cities.

Perth continues to be the fastest growing city in the country, with the population swelling by 3.2 per cent (52,200 people) last year, followed closely by Darwin, where the population grew by 3.1 per cent.

The total population of Australia is 21,374,000.