Private schools have slammed “glossy marketing campaigns” aimed at parents for inflating what they argue is the true cost of education to sell financial products.

As families increasingly consider financial planning to prepare for the rising cost of private schooling and university, independent schools have cautioned some of the costs portrayed are inflated.

The Australian Scholarship Group released new research this week that estimated the average median cost of an independent school education was $298,689 for each child, rising to up to half a million dollars for the richest private schools in Australia.

The estimates take into account school fees, estimated at $4196 over average for a Catholic school, but also other annual expenses including transport ($401), uniforms ($447), external tuition ($577) and devices ($1021).

But even without private tuition, the ASG Planning for Education Index found the average median cost of a government education in regional Australia is $57,994 over 12 years, urging parents to plan for the future with their financial products.

The Australian Scholarship Group offers parents tax-effective savings plans – not scholarships – to pay private tuition and university fees. But like any investment, it carries risks in terms of annual returns.

“Education costs, including tuition costs, uniforms, transport and devices, are demanding a far greater share of the family budget than in the past,” ASG chief executive officer Ross Higgins said.

But the Independent Schools Council of Australia (ISCA) said the big estimates of the cost of private schools were over-egged.

“While ISCA supports parents using sensible financial strategies to help provide for their children’s schooling, parents should note that school fee estimates used in the marketing material of these products do not reflect the fees of the majority of Independent schools,” ISCA executive director Barry Wallett said.

“The most recent official data available shows a median Australian metropolitan Independent school fee of $6685 per annum. Nationally, more than two-thirds of metropolitan Independent schools are charging below $10,000 per annum.

“In addition, there are numerous ways parents can save on costs; with many Independent schools offering scholarships, all-inclusive fees, and discounts for siblings or lump sum payments. ISCA strongly encourages parents to do their own research on the fees of the schools that interest them.”

The cost of education has long run at more than twice the rate of inflation.

But ASG stressed that private tuition fees are only part of the equation, with the cost of laptops, iPads, camps, sports and extra-curricular programs taken into account by its index.