Australia's richest people have become even richer in recent years - but their generosity hasn't followed the same trajectory.
The wealth of Australia's top 200 richest people grew by 15.7 per cent in the past year, up to $555 billion, according to the Centre of Social Impact.
And yet their charitable donations dropped, decreasing by 2.3 per cent in the same period.
If those same well-heeled Australians donated only one per cent of their wealth to charity, that would mean an extra $5.55 billion for the philanthropic sector.
"We really want the wealthiest Australians to consider what they can do to make a significant difference in the world," Philanthropy Australia chief executive Jack Heath told AAP.
But encouraging billionaires to give away more of their wealth requires speaking to them in a "way that moves them", he added.
"We need to get more of the stories out there where people have actually experienced such an enormous sense of joy from giving.
"By giving things away, you end up getting more coming back to you."
High-profile donations like a recent $250 million pledge from businessman Geoffrey Cumming to establish a global pandemic therapeutics centre in Melbourne could also encourage other wealthy people to give big, Mr Heath said.
"When they say look, someone in a similar position to me is giving and they seem to be getting more out of this than I ever expected, they also think about giving," he said.
"It's very much that peer-to-peer inspired giving model that we want to promote."
Introducing reforms that would enable more charitable organisations to receive tax-deductible gifts could also encourage more wealthy donors to contribute, Mr Heath said.
Philanthropy consultant Nigel Harris said charities needed to be smart about how they approached wealthy people for donations.
"It's about the relationship that's forged with the donor about the purpose that is being served, rather than just the money," the managing director of Nigel Harris and Associates said.
"The money is a means to an end - it's not the means. Rather than moving people to get money, spend far more time and attention in engaging donors."
Changing the national culture around philanthropy could also help encourage a larger number of the most affluent to give back.
"By and large, we don't like to big note ourselves in Australia," Mr Heath said.
"I know of a number of individuals who have given significant amounts but have done it very privately, not wanting any publicity.
"I think we need to effect a little bit of a change so people become happy to share their stories of giving.
"What we want to do is to communicate the joy that comes from giving."