When will Melbourne reach 5 million people?

Recently The Age published an article claiming that Melbourne's population was about to hit 5 million - specifically on 1 September 2018.  Naturally this intrigued me, and I wondered how this conclusion was reached.  My recent blog on population milestones did not even discuss Melbourne reaching this mark in 2017 or 2018.  The article in The Age was more about the history of Melbourne and did not elaborate on how this was calculated other than to suggest it was on the basis of new estimates from the ABS.  Did Melbourne's population reach 5 million?  Let's have a look at the evidence.

Melbourne - how is it defined?

Well I'm glad you asked because there are three main ways that Melbourne is defined from a statistical/spatial perspective.  There's the Melbourne Significant Urban Area (SUA), Melbourne metropolitan area (the total of the 31 metropolitan LGAs) and there's Greater Melbourne GSSCA, which is an even larger area that includes Gisborne, Bacchus Marsh and the southern part of Mitchell Shire.  All these areas can be referred to as "Melbourne" and the ABS regularly publishes ERP data for these geographies.

What is the population of Melbourne?

The table below shows the ERP for each of these Melbournes at 2016 and 2017, using the revised estimates published by the ABS at the end of August.

It shows that the population of Melbourne ranged from 4.67 million for the SUA to 4.84 million for Greater Melbourne.  Regardless of the geography used, the population growth rate for 2016-17 was 2.7%, placing the city as the fastest growing of the state capitals.

Interestingly, the revised estimates published by the ABS resulted in a lower population figure for Melbourne by almost 11,000 at 2016.  This of course pushes the 5 million population milestone a little further into the future.

Melbourne @5 million

Hmmm, sounds like a name for a metropolitan planning strategy.  But seriously - how did The Age calculate that Melbourne reached the 5 million milestone on 1 September 2018?

My own calculations suggest it hasn't quite reached this benchmark, even for the larger Greater Melbourne area.

In 2016-17 the population of Greater Melbourne grew by 129,400.  This equates to approximately 355 people each day.  There is no further information available to see if this has changed.

If we assume that Melbourne will grow by the same volume in 2017-18, this results in a population of 4,973,175 - still more than 25,000 short of 5 million.  The daily volume of growth - 355 people - results in an additional 22,010 people at 31 August, or a population of 4,995,185.  This is still almost 5,000 short of the 5 million milestone.

If the population continues to grow by 355 people per day, the 5 million benchmark will be reached on or about 13 September 2018.

I'm genuinely interested to know how The Age calculated that 5 million would be reached on 1 September, but they haven't responded to my Tweet.

Of course this is a very rough population forecast - to do it properly you would need assumptions around the components of population change and additions to the dwelling stock.  These estimates are really more a result of my curiosity, but they do show that perhaps Melbourne isn't quite ready to celebrate the 5 million milestone - yet.  The ABS will release 2018 population estimates for Melbourne (and the rest of Australia!) in April 2019.  Ultimately, this is the evidence base - even if 5 million was reached seven or so months earlier.

Melbourne is growing strongly, but has the city reached a population of 5 million?

Summary

There's no doubt that Melbourne (however defined) is currently experiencing strong population growth.  The city is about to reach a population of 5 million - I'm just not convinced it has yet.  My rough and ready calculations suggest 13 September 2018 is a more likely date.  In the end population milestones are just that - there's little doubt that a city of 5 million people faces significant planning challenges as it continues to grow and change.  Ultimately, data released by the ABS provides the evidence base for population milestones.