The figures, based on a sample of 57 charities, show that an average expenditure of £223,000 on legacy promotion generated an income of £9.89m.
"This return on investment is about as good as you're going to get in the fundraising world," Joe Saxton, founder of nfpSynergy, told delegates at the convention yesterday. "But you have to be in legacies for a long time - at least 10 years - to get results."
The least profitable form of fundraising, according to the research, was individual giving. An average expenditure of £1.84m generated a profit of less than £400,000.