The party is arguing that more seats, to be achieved by reducing the area of some, are needed to improve representation for regional and rural areas.

Today's Legislative Assembly has 93 members compared to 109 in 1988.

The National Party analysis shows 18 inner Sydney-based seats, which represent more than a million voters, do not go close to covering the area of the state's largest seat Barwon.

Barwon covers 44 per cent of the state's landmass but has 55,000 voters.

There are presently 5,303,980 voters in NSW, an average of 57,032 voters per seat.

If there were 109 seats the figure would be 48,660 per seat.

It would still be the largest voter per seat ratio in Australia.

"In the greater Newcastle area (Newcastle, Port Stephens, Maitland, Cessnock, Charlestown, Lake Macquarie and Swansea) we estimate there would be 9.4 seats. At least one of those seats would be marginal," NSW National Party state director Ross Cadell said.

Mr Cadell said the party had not considered where the potential new Hunter seats would be located.

"We want to give people the opportunity to vote on our proposal," he explained.

The National Party MPs who hold the Hunter's two largest seats, Myall Lakes and Upper Hunter, welcomed the proposal to reduce seat sizes.

Upper Hunter MP Michael Johnsen said it took him five-and-a-half hours to traverse his electorate.

"It's always difficult for constituents to meet their member if the member doesn't travel as much as I do," he said.

"When not in parliament I spend nearly all my time travelling around the electorate meeting as many people as possible."

Myall Lakes MP Stephen Bromhead, highlighted the fact that his seat was 5023 square kilometres compared to the seat of Maitland, which is 391 square kilometres, and Manly (31 square kilometres).

"If we don't take a stand now and Sydney continues to increase in population and seats in the parliament, the NSW Parliament may as well be the Sydney Parliament and that's where all the money will flow," he said.

But, Labor's Jodie Harrison, who holds the Hunter's smallest seat, Charlestown, said creating more seats was not the answer.

"It's not the ground that votes, it's the number of people in it," said Ms Harrison, whose seat covers 66 square kilometres and has 55,813 voters.

"I don't think more seats will automatically give people an improved voice.

"It comes down to the MPs to ensure their constituents are well-represented.

"Larger electorates get additional resources to help those MPs engage with their constituents.

"I doubt the average voter would want to see more people in parliament."