Often they care for a baby whose parents can't find enough daycare placements while others care for children before and after school.

In fact there are estimates that almost one in four children receives at least some care from their grandparents.

Not only does this save the families money, it also gives some parents an increased sense of well-being in knowing their family is being cared for by family members.

Often it's the grandparents who take them away on trips during the school holidays.

As an added, and very important bonus, it also helps grandparents develop a bond and relationship with their grandchildren which they may not have been able to do in other circumstances.

Australian grandparents are contributing the equivalent of $3.94 billion annually in childcare costs, by minding their grandchildren, according to the survey of 1000 people conducted by comparison site Mozo.

Typically a grandparent-carer is contributing about 30 hours a month, however not all grandparent/carer relationships are the same.

Unlike some grandparents who are free from the pressures and responsibilities of actually raising these children, some grandparents find themselves in a role they likely would have long thought was long behind them.

For whatever reasons, and often they involve significant emotional distress and trauma, these grandparents are effectively forced to parent their grandchildren.

Allowing their grandchildren to be placed in the care of the state is simply not an option many would countenance, so they selflessly put up their hands to help the vulnerable and needy children they dearly love.

And, in doing so, they suffer for it, being at a greater risk of poverty and ill health.

Former Children's Commissioner Mark Morrissey wants a state government inquiry into the issues faced by this growing group in our community.

"The desperate circumstances of many grandparents need to be recognised and addressed," Mr Morrissey said.

"Elderly grandparents already fully occupied in raising grandchildren should not be in a position where they are also having to lobby and agitate for 'a fair go'."

But they are.