More people than ever before will be paying off their mortgage long after retirement, according to new figures, which reveal a rise in the number of 40-year mortgages on offer. But while the new 40-year terms make buying more affordable, they may cost you more in the long run.

House prices, growing life-expectancy and people working for longer have all contributed to the trend. A rise in the age at which people have children and higher student debt commitments are also thought to be factors.

The research, from financial data website Moneyfacts, reveals that 51% of mortgages currently on sale have a standard maximum term of up to 40 years. This is a rise from 36% five years ago.

The average first-time buyer in the UK is aged over 30, meaning that with a 40-year mortgage, most would be into their 70s before becoming mortgage-free.

With people struggling to get on the housing ladder, a loan with a longer repayment term can mean more affordable monthly mortgage payments.

According to Moneyfacts, a £200,000 repayment mortgage at a rate of 2.5% would cost £897 a month over 25 years or £659 a month if the borrower signed up for a 40-year term.

However, borrowing over 40 years is likely to cost far more in the long-run than the standard 25-year term. The same £200,000 loan over 40 years would cost £47,000 more in extra in interest.

While paying off your mortgage in your 70s may feel like a long stretch, such 40-year terms are short in comparison to some deals, which have been available globally. Ten years ago, a US firm launched a 50-year mortgage. And in 1990s Japan, high house prices led to the 100-year mortgage, designed to be passed on to the borrower’s descendants.

Read more about this story in The Guardian.