Western Australia could have a diminished role to play in the next federal election, with population estimates putting the state in serious danger of losing one of its seats in Federal Parliament.

The situation, described as "unprecedented" for WA by one political analyst, could see the number of WA members of the House of Representatives reduced from 16 to 15 after the next federal election.

So why is this happening? And what would it mean for WA?

How many seats do the states get?

Unlike the Senate, where each state gets 12 representatives, the number of Lower House seats in each state is determined by population.

There were 151 seats up for grabs in the House of Representatives at the 2019 election. ( ABC News: Timothy Stevens )

The Australian Electoral Commission uses a formula which determines each state's entitlement, based on its population.

That means New South Wales, the most populous state, gets the highest number of seats with 47 while Tasmania gets just five, the ACT gets three and the Northern Territory gets two.

What is WA's situation?

WA currently has 16 seats, a number that has regularly increased over the past century amid the state's population growth.

That increased from 15 to 16 just a few years ago, in time for the 2016 election, when the seat of Burt was created in Perth's eastern suburbs.

Labor's Matt Keogh claimed victory in the WA seat of Burt in 2016, after its creation in 2015. ( ABC News: Courtney Bembridge )

Of those, 11 are held by the Liberals and four by Labor. One seat — Cowan — remains in doubt, but Labor's Anne Aly is ahead and considered likely to hold on.

By the numbers

A complicated formula is used to work out how many people are needed in a single electorate — using something known as the "population quota".

The population quota is the number of people in the country (just under 24 million at last count) divided by double the number of senate seats from the states (72 x 2 = 144).

That works out to about 165,000 people per electorate.

To work out how many seats each state gets, you take the number of people in each state and divide by the quota.

Here's how it was worked out in August 2017:

State/territory Population Result MPs New South Wales 7,797,791 47.31996 47 Victoria 6,244,227 37.89234 38 Queensland 4,883,739 29.63639 30 Western Australia 2,567,788 15.58231 16 South Australia 1,716,966 10.41920 10 Tasmania 519,050 3.14979 5 Australian Capital Territory 419,256 2.54420 3 Northern Territory 247,512 1.50200 2 Total Lower House MPs 151

You may notice a few anomalies here. Tasmania should get three seats according to the calculation, but it actually gets five because it's guaranteed that number by the Australian Constitution.

Why could the number of seats change?

WA's population is still growing, but at a slower rate than other states.

WA's population growth is slower than other parts of Australia. ( ABC Radio Perth: Gian De Poloni )

That means WA is now below the threshold that sees it entitled to 16 seats, which would force the AEC to redraw the boundaries and abolish one electorate in the west.

There is still time for that to change as the cut-off is not for another year, but without a population surge between now and then, WA is set to lose a seat.

"If the population trend remains in a year's time, will see it lose a seat," research provided to MPs by the Parliamentary Library states.

Which seat would go?

That bit is very difficult to say. Political parties will do their bit to influence the process, making their own proposals to the AEC about what should happen.

"If WA were to lose a seat, there would be a fairly furious submission war between the two parties about where that should happen," Notre Dame University political lecturer Martin Drum said.

"It will be about trying to preserve their existing seats and perhaps pinch one off the other team."

While the AEC runs a public comment period — during which the political parties and other interested observers make their own suggestions — the Commission has the final call.

But the abolition of any seat will lead to a much wider redrawing of the map, with those voters accommodated in neighbouring electorates.

Who would pick up WA's lost seat?

Technically, that seat could just disappear and the House of Representatives be reduced in size by one, because the Lower House does not have a set number of members.

But research by the federal Parliamentary Library shows Victoria's share of the population is increasing significantly, potentially fast enough to push it over the threshold to gain an extra seat.

Victoria, where Treasurer Josh Frydenberg held his seat of Kooyong, currently has the second-highest number of Lower House seats out of every state and territory. ( ABC News: Danielle Bonica )

What could it all mean for WA?

Veteran WA political analyst Peter Kennedy said having fewer seats in Federal Parliament could diminish the amount of attention major parties paid to the west, particularly during campaign season.

"Politics has always been a numbers game. The more seats you get the more attention you get," Mr Kennedy said.

"The leaders go to the seats where they are likely to get the biggest bang for their buck."

Australian Prime Minister Scott Morrison and former opposition leader Bill Shorten made the journey west a number of times in the campaign. ( AAP: Nic Ellis )

Dr Drum also pointed to the possibility that sitting MPs could be left battling each other for a single seat — potentially even MPs from the same party.

"It might result in some kind of scramble for existing MPs to keep their seats," he said.

What about the names of the seats?

If an electorate does get abolished — and others end up looking very different — it could result in some new names for WA's seats.

Labor Member for Perth Patrick Gorman said he hoped that resulted in the AEC naming a seat after former prime minister Bob Hawke, who died just two days before the Federal Election.

"He spent his schooling years here and he has always been loved by Western Australians," Mr Gorman said.