Parents of a child born this year can expect to pay almost $40,000 for their education, after big rise in costs over the last 10 years.
It's prompted critics to claim there's "no such thing as a free education".
The price of a child's state education has risen by 15 per cent since 2007, figures released by the Australian Scholarships Group (ASG) Planning and Education Index today show.
And if you're flush enough to send your child to a private school, you can now expect to pay 48 per cent more than parents a decade ago.
The estimated cost of sending a child born in 2017 through 13 years of a private education is now $345,996, a jump of more than $110,000 compared to 2007.
For that same child to go through a state-integrated education it will cost their parents $109,354, a rise of 34 per cent over the same period; while a state education has climbed to $38,362.
The data compiled by ASG for the index is based on 2000 responses and measures a range of costs including school fees, transport, uniforms, computers, and school trips.
The cost of education in New Zealand has risen by double the rate of inflation over the past decade, according to John Velegrinis, ASG chief executive.
"This is quite significant because the underlying trend is that this gap between the costs of education and the CPI is continuing to expand over time," he said.
"For low income parents there is continued pressure on family budgets particularly during a period where we've seen historically low income growth."
New Zealanders were fortunate to have excellent state, state-integrated and private schools to choose from, but costs could spiral out of control.
"There is no such thing as a free education," Velegrinis told the Herald.
"Even if a state school does not charge any fees, parents still need to meet the cost of a range of items, such as uniforms, text books, computers, extra-curricular activities etc."
The introduction of digital devices in the classroom had been the biggest driver to increasing costs for parents, he said.
"There continues to be greater pressure on family budgets and parents need to make choices around what has to give in order to provide that education."
He advised parents to take a disciplined savings approach, which focuses on regularly putting modest sums away.
"You plan for retirement and buying a house, these are major life events. Education is another major life event which needs equally appropriate planning."
Labour's education spokesman Chris Hipkins said the Government wasn't living up to its promise of a free education, and kids "haven't been getting that for some time".
"The current National government's freeze on school funding will have only made this worse. Government funding simply hasn't been keeping up with the cost of educating kids.
"If they don't get the money from government, schools have to look elsewhere and parents are the ones most likely to end up footing the bill. It's as simple as that."
The Ministry of Education's acting head of sector enablement and support, David Wales, said the Government had increased its per student funding by 38 per cent in the 10 years to 2015, to $7333.
"The Government pays most of the education costs, with donations making up a small part of school budgets overall," he said.
"For every $1.80 parents donate to schools, taxpayers contribute about $100.
"It's important that parents know that any donations their school asks them for are voluntary. The right to free enrolment and free education means that Boards of Trustees may not charge a fee for enrolment or attendance of domestic students."
The Government had increased decile funding by 23 per cent, he said, and also offered subsidies for transport and board.
'It makes you query the 'free' in free education' - mum
"Luckily our boys don't do a lot of sports," Glen Innes mum-of-two Tsana Plessius jokes as she lists off the costs of the new school year.
With two growing boys, aged 11 and 13, uniform costs are top of the list - with oldest son Karl starting secondary school at Selwyn College, a whole new uniform had to bought.
"And all the stationery requirements, and these days both of our boys have their own devices, so that adds significant costs to it all."
Robin, 11, who attends Tamaki College, will do most of his schooling this year on his netbook. However, Karl's stationery pack cost $90, "plus there's extra bits that aren't in that pack depending on what classes he's doing, plus there's a netbook".
School and PE uniforms were expensive, church administrator Plessius said, with one pair of shorts costing upwards of $50 to $70, and each son requiring two pairs.
She had yet to add up what they had spent for the start of term, she said, but it was likely in the hundreds of dollars.
And there are always extras on top of the essentials - like school trips, donations and extra tuition for the boys.
School donations, while supposedly voluntary, often felt mandatory, she said.
"There are constant reminders, you know, 'thank you to those who have paid the donation, and just a reminder please pay'; and that's on top of everything else.
"And if you don't pay it, you get the reminders and you do feel ... people are going to know."
The decile 1 school where the boys went to primary stopped asking for donations, she said, because so few people were able to afford to pay it.
"They talk about free education, but when you have costs like that [$3146 for a state education] it does make you query the 'free'.
"There's a lot of people in our area with large families, and a lot of families just wouldn't be able to afford that for their children."
Plessius said she was lucky that her and husband, design engineer Eric, could meet the costs, and be able to afford extra tuition for the boys.
Son Robin is an advanced maths pupil and has skipped ahead to Year 11 this year. He needs a specialist maths tutor, and Karl has also received outside help with his maths.
"That's added costs, and it's something we don't need to do, but we feel it's important for the boys to have those opportunities."