The percentage of wills containing at least one charitable bequest has recovered from a low of 10 per cent in 2002 to 15 per cent now, according to a Charity Monitor survey. The last time the figure was this high was in 1997.
The figure means that 4.3 per cent of UK adults are making charity bequests, said the charity data service.
Will-making among UK adults has risen to an unprecedented 38.5 per cent, up 3.5 percent on a year ago, with new wills coming particularly from men and people aged 35 to 54.
Charity Monitor founder Andrew Papworth said: "Even allowing for the possibility of sampling variation and a freak result, this looks very promising. The projected numbers are quite mind-boggling in terms of a growing market for fundraisers to aim at."
But a Grant Thornton survey of 170 charities with income of £1m or more, showed legacies are worth 4.46 per cent of total income, down from 5.14 per cent in 2002.