The average online donation fell by 8.6 per cent to £63.69 in 2014 compared with the previous year, according to the latest figures.
But the figures, from the software and services company Blackbaud, show that the average online gift was up by 13 per cent on the previous year to £78.59 if donations made as a result of the ice bucket challenge were excluded. The challenge led to a high volume of small donations.
The data, published today, is based on 289,000 donations made to 295 UK-based not-for-profit organisations, including charities, arts and culture bodies and educational organisations.
It shows that the average online gift has increased by £10.87 over the past five years, up from £52.80 in 2010.
Blackbaud said the inclusion of educational organisations in the sample meant the average amount was higher than other studies have shown because people tended to donate significantly more to that sector.
Jerome Moisan, managing director for Blackbaud Europe, said the figures showed the importance for charities of ensuring they were in a position to capitalise on any future viral campaigns that might cause overnight interest in their causes.