The figure is the most definitive yet on the degree to which the UK voluntary sector lost money because of the tsunami.
According to UK Giving 2004/5, a survey that is out this week, people gave an average of £5.04 to tsunami appeals. Of this, about £4 was money they would not normally have given to charity, but £1 was diverted from other causes.
Susan Wainwright, research officer at the NCVO, which compiled the survey with CAF, said the figure was "obviously good news for charities because we're not seeing much displaced giving.
"When you think about it in the grand scheme of things, when people give a total of £8.2bn, that £48m is really tiny," she added.
But Brendan Paddy, head of media at ChildLine, said the impact of tsunami giving had been disproportionately felt. The worst affected were those engaged in fundraising when the tsunami happened, such as ChildLine, and small to medium-sized organisations, he added.
Debra Allcock Tyler, chief executive of the Directory of Social Change, said the figures only reflected losses resulting from the tsunami appeal. "There have been five major appeals this year, the others being for Niger, the London bombings, New Orleans and the Pakistan earthquake," she said.
The NCVO advised charities that saw their voluntary income dive as a result of the tsunami to introduce measures to prevent a similar situation in future.
"Charities should try to encourage donors to use planned and regular methods of giving," Wainwright said.
The survey also showed that disasters such as the tsunami and faith-based causes attracted the most interest from high-level donors - those giving at least £100 a month.
It said that less successful causes, such as disability, the elderly and young people, must work at raising their profile among these donors. They account for just 5 per cent of donors, while providing about 40 per cent of the total amount given.