Research indicates that people who use mortgage brokers borrow up to 10 per cent more than the average home buyer.
The average mortgage comprises 70 per cent of the value of a property, according to a study released last week from peak accounting body CPA Australia.
But those who used a broker borrowed nearly 80 per cent of the property's original value.
It is not clear if brokers' commissions or another factor was a driver in the loan difference, CPA Australia financial planning policy adviser Kath Bowler said.
Research house Insight Compass surveyed 312 mortgage holders in each Australian state between May and June this year.
Despite a rise in the use of mortgage brokers, the study found that home buyers still rate relationships with lenders and banks highly when choosing their loan.
According to the research, 43 per cent of people selected their mortgage because of existing relationships, with those aged over 55 much more likely to do so than younger people; 27 per cent of people surveyed used a broker to source their current mortgage.
Fees and rates were the second most popular reason to choose one mortgage product over another.
Only seven per cent said an accountant, financial planner or another professional was the largest influence in choosing their loan.
The research also found that one in four people did not know the interest rate they paid when they took out their mortgage.
"It is almost as if people are turning a blind eye to the cost when choosing a home loan," Bowler said.
The older the buyer, the less concerned they are about interest rates.
More than half of buyers also wrongly conclude that they are not paying extra for features of their loan.
Interest rate data from the six major banks showed that on average, mortgage holders pay 0.67 per cent more to have an offset facility and 0.68 per cent to have a line of credit.
"That's equivalent to over $34,000 extra you will pay on a $250,000 loan over 25 years," research group Cannex spokesperson Mamta Grewal said.
