How much would you consider paying for an apartment where the bedroom isn't quite its own room but is separated by a sliding door that opens up onto the lounge room?

This one-bedroom apartment at 21/108 Elizabeth Bay Road, Elizabeth Bay has just set the bar quite high - it's on the market for $2.1 million.

Most people would consider this a studio, but it fits the definition of a one-bedroom, according to the NSW Department of Planning Apartment Design Guide, because it comes with "a window in an external wall with a total minimum glass area of not less than 10 per cent of the floor area".

It offers extensive harbour views from the bridge right around to the heads with two private balconies, and an open plan living and dining space. The "Oceana" building itself is perched on the tip of Elizabeth Point, next to Beare Park, and has a common harbourside pool, jetty and BBQ area.

And if you need even more flexibility with your living arrangements, the bedroom is separated by a sliding door that can be removed completely - effectively making it a studio. Perfect if you want to watch the sun rise over the harbour, or clock the New Year's Eve fireworks after you've already gone to bed.

It used to be a two-bedroom apartment, but agent Jason Boon said renovations were undertaken so the owners - a couple from Canberra who use it as their Sydney base - can enjoy the views from the entire apartment.

And with 100 square metres of space it's much bigger than many of Sydney's smallest studios and one-bedroom apartments.

The median apartment price for Elizabeth Bay over the past six months is $870,000, according to Domain Group data, with 8 per cent price growth over the past year. Prices in the suburb have ranged from $350,000 to $5,050,000.

The NSW Department of Planning Apartment Design Guide stipulates that the minimum floor space for a studio apartment is 35 square metres, and for a one-bedroom apartment, 55 metres.

In 2015, first-home buyer Jae Jun Kim was shocked to discover his one-bedroom, off-the-plan apartment purchase in the Sydney CBD was actually a studio. There had been a "discrepancy between the architectural drawings that we submitted to council and the detail in the sales documents for that particular unit", according to the project manager.