Volunteer organisations face a recruitment crisis as the amount of time young people give up for free has more than halved since 2000.
The average time people aged 25 to 34 spent volunteering has fallen dramatically from 15 minutes a day to six minutes a day, according to figures from the ONS.
Professor John Mohan, director of the Third Sector Research Centre, said that the recession meant they could not afford to volunteer.
"That age group were entering the workforce when the recession hit. They've had much less choice over the jobs that they've taken, and many of them are working part-time and zero-hours, so that's going to have an effect on their ability to volunteer," he said.
He said voluntary organisations were already finding it harder to recruit.
The overall time spent volunteering has fallen by 7 per cent since 2012, at a cost to the economy of more than £1bn.
This week the Scouts said that they had a waiting list of 46,000 children and desperately needed more volunteers to run sessions.
Nick Ockenden, of the National Council for Voluntary Organisations, said that the average minutes had also fallen because young people were increasingly engaged in "micro-volunteering" which can be done on a smartphone.
We have a situation where there is increased demand at the same time that volunteer organisations are finding it hard to recruit
Dr Daniel Wheatley
Projects such as Zooniverse, which allow people to help with research by doing work such as examining photos or translating documents, are an increasingly common way for people to volunteer.
There is also evidence that older people are retiring later, leaving less time available for volunteering.
Over-65s now spend an average of 13 minutes a day volunteering, which has fallen from 19 minutes in 2000.
Dr Daniel Wheatley, a senior lecturer in business and labour economics at Birmingham University, said that there is an increasing need for volunteers as local authority funding cuts mean they are needed to help provide resources such as childcare and respite care for disabled people.
"We have a situation where there is increased demand at the same time that volunteer organisations are finding it hard to recruit," he said.
Meanwhile the time given by those aged 16 to 24 has increased dramatically from nine minutes a day to 17. Experts said this was because teenagers were increasingly told volunteering was necessary for them to get a job later on.