Melbourne's population is expected to almost double to 7.7 million by 2051, as latest figures show that interstate migration is on the rise.

"Indeed, more people now leave Queensland than leave Victoria to come and live here than vice versa," said Victoria's Planning Minister Matthew Guy, indicating a reversal in the trend of recent years.

Currently, 4.25 million people live in the Melbourne metropolitan area, compared with 4.76 million in Sydney.

However, the Victorian Government's planning blueprint, Plan Melbourne, indicates the city's population will swell to 7.7 million people over the next four decades.

The population figure has been revised upward from a forecast of 6.5 million late last year and is in line with projections by the Australian Bureau of Statistics (ABS) that Australia's overall population will grow to more than 40 million by 2061, from 23.5 million today.

Mr Guy says the state's net population growth is being driven in part by migration from interstate.

"We are actually now seeing thousands of people coming from interstate for the first time, on a net basis," he said.

Last year, Victoria gained more people from interstate migration than any other state or territory, according to the ABS.

Mr Guy says population growth is good for the state, but needs to be targeted to specific areas and properly planned for.

The Plan Melbourne document includes a focus on developing Victoria's regional towns and centres to take the pressure off Melbourne.

Planning Institute of Australia's Victorian president Brett Davis says the government needs to ensure public transport infrastructure keeps up with the growing city.

"In inner to middle Melbourne it's excellent, in a regional sense it's fine, the challenge is providing that level of service delivery to the outer suburbs," he said.