A third of Londoners cannot afford a decent standard of living because of extra costs of living in the capital, such as housing and transport, according to a new report.
Research for the charity Trust for London showed that for some people in London it costs up to 50% more to reach a decent living standard compared to the rest of the UK.
Food, travel costs and rent were all higher in London, with a single person in Inner London spending £410 a week to live, including housing and childcare, £130 more than the UK average, said the report.
The study among 21 focus groups, by Loughborough University, also found that housing, childcare and transport costs in London had risen sharply since 2008.
Mubin Haq, director of policy and grants at Trust for London, said: "The very high costs of housing, transport and childcare mean one in three Londoners are struggling to live a decent life, especially families with children.
"This is not about just food, clothing and having a roof over your head. It's about the difference between people being able to participate in society or not.
"It raises important questions about whether London is for everyone or does it become a city for the wealthiest.
"To help more Londoners reach the minimum we need a two-pronged approach which tackles low incomes, particularly low wages, coupled with policies to bring down the costs of housing, transport and childcare."
Campbell Robb, chief executive of homelessness charity Shelter, said: "All too often, we hear from families in the capital battling to keep up with their housing costs, so sadly it's no surprise that sky-high rents are leaving millions of Londoners are struggling to afford a decent standard of living.
"Soaring house prices and decades of not building enough homes has created an affordable housing drought in London, forcing more and more people into in expensive and unstable private renting while they watch huge chunks of their pay packets fly out the window every month."
TUC general secretary Frances O'Grady said: "British people have suffered the longest fall in living standards since Queen Victoria was on the throne, and it's hitting Londoners especially hard.
"But even though we knew things were getting tougher, it's still a shock to learn that more than four in 10 of London's families are below a decent standard of living.
"The weak economic recovery is not delivering for working people and their families, unless you're one of the privileged few at the very top."