Covering the cost of a funeral without getting into debt would need quick access to cash for 41% of families, a poll by Engage Mutual has found.
When shown the average cost of a cremation or burial in Britain, 41% believed their families could get into debt without access to their estate within a week.
Those questioned underestimated the cost of a burial, with two thirds estimating £4,000 or less, while the UK average is £4,690.
When asked to estimate cremation charges more than half estimated the cost at £3,000 or lower , the average cremation in the UK costs £3,239.
After costs were revealed 16% of families said they "were shocked" by the cost of funerals.
The main reason for not making a provision for a funeral was a lack of money to save towards one, while 4% thought the state would pay.
The average length of time for probate to be completed on an estate is six months, 5% of those polled thought their families would have instant access.
Of the 2000 people polled, 56% had not made a will, which can lengthen probate.
Stuart Tragheim, sales director at Engage Mutual, said: "What's clear from our research is that when there's a death in the family, people need access to money and they need it quickly."
Tragheim added: "It shows how important protection is and how fast payment benefits such as the nominated beneficiary option, can be a valuable safety net."
4.7 million people living with the condition in the UK
Five reasons why
But L&G boss says it’s ‘not a major risk’
At the end of National Heart Month
Ruth Gilbert investigates another potential threat to life policies