Unpaid carers save the UK economy almost £60bn a year, suggests a new analysis of official figures by the Office of National Statistics.
About 8% of the UK population living in private households acted as informal carers last year, Department of Work and Pensions figures show.
The ONS calculates that it would cost £56.9bn to replace these unpaid carers with paid workers.
Both sexes spent more time on unpaid care in 2015 than in 2000, it says.
The ONS links the rise in unpaid care by family members to “a rapidly ageing population and a higher life expectancy”.
“At age 65 a man will spend, on average, 44% of the rest of his life in poorer health, and a woman, 47% of her life,” says the ONS document.
Women are more likely than men to be informal carers, with women making up 59% of carers.