Women can expect to take on caring responsibilities for an older, sick or disabled relative more than a decade earlier than men, a report concludes.
Research by Sheffield and Birmingham universities shows half of women will care by the age of 46, compared with half of men, for whom the age is 57.
The research suggests two-thirds of UK adults can expect to become an unpaid carer during their lifetimes.
The charity Carers UK says carers need five-to-10 days of paid care leave.
For the charity's report - Will I Care? - the academics analysed data from individuals who had participated in both the British Household Panel Survey and Understanding Society social and economic study for more than 15 years between 1991 and 2018.
Their findings showed 65% of adults had provided unpaid care for a loved one.
Women had a 70% chance of becoming a carer and men 60%.
By the time they were 46, half of women had been a carer, the researchers found, while with men, it was not until they reached the age of 57 that they had the same 50-50 chance of being a carer.
Most carers were middle-aged - almost half (46%) aged 46 to 65 - and the average person has a 50-50 chance of becoming a carer by the age of 50, according to the researchers' data.
Ravi has cared for her elderly father on and off for 26 years since her mother died.
But the responsibility intensified 12 years ago when her father, who's in his 80s, underwent open-heart surgery - and the past year and a half has been particularly taxing, after he suffered a stroke in 2018.
Ravi, from Hounslow in west London, is now in her 50s. She told the BBC she spent about six hours a day caring for her father - she cooks for him, checks his blood sugars, administers medicine, acts as his advocate, as the stroke has led to impaired speech, and deals with correspondence.
She also works full-time as a residential social worker and says her caring responsibilities have had a major impact on her health.
"You get to a point where you think, 'I can't take it any more', and you have to step back and get yourself into a good place before you can go on.
"Sometimes I say things I shouldn't say, but as my manager said to me, 'You're only human'.
"I've got a lot of patience and understanding but when I'm not feeling 100%, or if I'm tired, then it's hard to keep my composure."
The emotional fallout from her father also takes its toll.
"I'm having to deal with his frustrations and emotion - I get the brunt of that frustration. He gets a lot more agitated than he used to."
Ravi says more support for people like herself - including paid carer's leave - would be welcome.
"As a wider society, I think people see you and think you're fine and you look OK on the surface, but it's really stressful and draining."
'A heavy price'
Lead report author and head of the Sustainable Care programme at Sheffield, Prof Sue Yeandle, said: "Caring is vital for us all and a precious support for those we love at critical times.
"Provided by millions of women, care also features strongly in the lives of men. Yet too often carers pay a heavy price for the support they give - financial strain, poorer health, social isolation."
Helen Walker, chief executive of Carers UK, said: "Many of us don't expect to become an unpaid carer but the reality is two in three of us will do it in our lifetimes.
"Our research shows women are disproportionately affected, facing difficult decisions about their loved ones' health, family finances and how best to combine paid work, and care more than a decade earlier than men."
The charity is calling on the next government to commit to delivering long-term investment in social care and give carers a right to five-to-10 days of paid care leave.
The carer's allowance has not been subject to the benefits freeze.
In November, the Department for Work and Pensions said it would rise by 1.7% from April 2020.
Labour's social-care and mental-health spokeswoman Barbara Keeley said: "Nine years of failure to fund social care properly means that carers are picking up the pieces of a broken system.
"A Labour government will help carers by introducing free personal care for older people and we will raise the carer's allowance for full-time unpaid carers in line with job-seeker's allowance, and deliver an updated national carers strategy."
Liberal Democrat health spokeswoman Luciana Berger said carers were "unsung heroes".
"In government, Lib Dems will introduce a statutory guarantee of regular respite breaks for unpaid carers and require councils to make regular contact with carers to offer support and signpost services.
"We will also provide a package of carer benefits, such as free leisure centre access, free bus travel for young carers and self-referral to socially prescribed activities and courses."
She said Lib Dems would also raise the amount people can earn before losing their carer's allowance from £123 to £150 a week, and reduce the number of hours' care per week required to qualify for it.
The Conservative Party has not yet responded to requests for a comment.