Thirty-one per cent of Australians volunteered with a not-for-profit organisation in 2014, down from 36 per cent in 2010, according to new Australian Bureau of Statistics data.

The general social survey revealed both men and women were less likely to donate their time. In NSW, 30.6 per cent had volunteered in the preceding 12 months – compared to 32.3 per cent in Victoria, 36.7 per cent in South Australia and 26.9 per cent in Queensland.

There was also a small decline in the proportion of Australians who helped out in other households – such as their neighbours' –to 46 per cent from 49 per cent, although the ABS said this was not statistically significant.

Chief executive of the Centre for Volunteering NSW, Gemma Rygate, said she was surprised and disappointed by the decrease in volunteering.

"It says that we have a lot of work to do," she said.

One explanation for the decline was that people were volunteering in ways that were not counted by the survey, Ms Rygate said. Many Australians are looking after their elderly parents rather than sending them to an aged-care facility, or doing unpaid, online work for government organisations such as the Australian Museum.

Such people should be recognised for their contribution, said Ms Rygate, who is pushing for the definition of volunteer work to be broadened. She rejected the idea that Australians were becoming more self-absorbed.

"I don't think people are more selfish. [But] there are so many external pressures on people these days that it makes it more difficult to commit to giving that time," she said.

ABS data showed 45 per cent of women and 36 per cent of women always or often felt pressed for time in 2014.

North Epping's Emily Smith, 23, has been a Girl Guide leader since she was 15 and was last year's NSW Youth Volunteer of the Year.

She said the sense of personal fulfilment that comes from donating even small amounts of time should motivate people to get involved.

"Those little bits and pieces; they're manageable time applications that really do contribute," she said. "Volunteering really is part of the lifeblood of our community."

Nominations for NSW Volunteer of the Year close on July 17.