Research from OnTheMarket shows that 40 per cent of London homes costing around £1m have only two bedrooms or fewer.
And only 10 per cent of the homes priced between £900,000 and £1.1m in the capital are either one-bedroom properties or studios.
It says that, perhaps unsurprisingly, Kensington and Chelsea is the most expensive London borough because it provides an average of 1.7 bedrooms within a £1m home. Westminster is second with 2.0 bedrooms.
The outer London boroughs of Bexley and Sutton are the best value because they provide an average of 4.5 bedrooms for £1m, says the portal.
When it comes to the rest of the country, only one in 20 homes for sale priced at £1m have two bedrooms or less.
In London as a whole, the average number of bedrooms purchased for £1million is three and across the UK, the average is 4.6. Outside the Capital, a one million pound property budget will stretch to up to 6.8 bedrooms in Merseyside and 6.7 bedrooms in Tyne and Wear.
Meanwhile the portal - which was set up by a series of high-end estate agencies - says its research shows that just 41 per cent of properties around the £1m asking price have parking; eight per cent have a driveway while 71 per cent “have access to” a garden.
“Despite a £1m home being way out of reach for the vast majority of buyers, this hefty budget still won’t buy a good sized family home throughout much of London. Nor does it guarantee the convenience of parking or the pleasure of a garden” says OTM’s Vikki Bennett.
“We also found that half of the homes currently for sale in London at this price are flats or apartments which underlines the difficulties facing families who aspire to own what they consider a ‘family home’ inside the capital.”
For those with a budget from £450,000 to £550,000 the average home in London in this range has 2.5 bedrooms.
Barking and Dagenham is the best value London borough which gives an average of four bedrooms for £500,000.