The publication of school achievement data will inevitably lead to "league table" comparisons being made, opposition parties say.
Education Minister Hekia Parata announced on Wednesday exam results, education review office reports and schools' annual reports would be published on a website from September 30.
The ministry isn't going to produce "league tables" comparing school performance.
Ms Parata says the data will be accurate but schools aren't all using the same format to present it.
The Green Party says it's inevitable that schools will end up being ranked.
"It is disingenuous for Ms Parata to say schools won't be compared with each other in a `league table' fashion," co-leader Metiria Turei said.
"People will seize on whatever data is uploaded on the ministry's website and make judgment calls based on that data."
Ms Turei, and Labour leader David Shearer, doubt the information will be accurate.
Mr Shearer says it won't present a true picture of student achievement.
Labour's education spokeswoman Nanaia Mahuta says the decision to publish the data was rushed through with little consultation.
The data will include national standards results - the benchmarks in reading, writing and maths that the government introduced against strong opposition from teacher unions.
Ms Mahuta says that's "a slap in the face" for the education sector.
Ms Parata doesn't believe it will be possible to make accurate comparisons between schools based on the data that's going to be published on September 30.
"There are 2436 schools and there is no `national test' that can rank them from one to 2436," she told reporters.
Ms Parata says 95 per cent of schools have submitted the data needed to launch the website on September 30 and she expects by then to have 100 per cent.