Unpaid care work in Scotland is worth £36bn a year, research from Oxfam suggests.
The analysis compared unpaid care work with current rates of pay in equivalent sectors to calculate the estimate.
The charity said this is more than twice the gross value added in Scotland by the financial services sector and almost four times the oil and gas sector.
Those living in or at risk of poverty tend to spend more hours caring, with the Scottish Government estimating 45% in the most deprived areas of the country care for 35 hours a week or more, almost double the level in the least deprived areas.
Polling commissioned by the charity suggested 72% of people in Scotland support more Government spending on social security benefits for carers of those who are sick or disabled.
The YouGov poll of more than 1,000 people found 81% of people in Scotland think unpaid care work is not valued highly enough.
The poll and analysis were published ahead of the Scottish budget and the annual World Economic Forum in Davos this week, with the charity saying a “broken worldwide economy” has concentrated wealth into the hands of a rich few by “exploiting the unpaid labour of millions”.
Oxfam said additional investment is needed to better value unpaid care work in Scotland, arguing such funds could create more and better jobs, lift people out of poverty and reduce inequality.
Rhiannon Sims, research and policy officer at the charity, said unpaid care work is “too often undervalued by society which can trap those who are providing it – very often women – in poverty”.
“If political leaders, whether at Davos this week or at UK or Scotland levels, are serious about reducing poverty and inequality, they urgently need to invest more resources to ensure this major contribution to our economy and society is recognised and better valued,” she said.
“We recognise the huge efforts of those who’ve long been highlighting the importance of unpaid care in Scotland, but more action is needed.
“When it comes to the Scottish budget next month and the UK budget soon after, the people of Scotland resoundingly support better valuing those delivering unpaid care.”
Fiona Collie, policy and public affairs manager at Carers Scotland, said carers face poorer health, greater poverty and more isolation than non-carers, and called for more investment in “high quality, flexible social care”.
Satwat Rehman, director of One Parent Families Scotland, said recognising and valuing the caring role of single parents is vital and called on the Scottish Government to further invest in flexible early learning and childcare support.
Oxfam has also released a global report, Time to Care, which shows women and girls are carrying out £12.5bn hours of unpaid care every day, with this contributing at least 10.8tn dollars (£8.28tn) a year to the global economy.
A Scottish Government spokesman said: “All unpaid carers play a vital role and we are committed to supporting them, which is why we are fully funding implementation of the Carers Act by providing £17.4m to local authorities in 2018-19 and an additional £10.5m this year.”
He pointed to further action in Scotland including the introduction of the carer’s allowance supplement and a grant for young carers.