HAM uses individual-level data on the income of renters in each area alongside what a lower quartile house would cost, leading to a much richer picture than other measures.

Housing affordability is still getting worse according to an official Government measure, with four in five renters unable to comfortably afford mortgage payments.

The Housing Affordability Measure's (HAM) latest results are only current to March 2017, but show that affordability then was worsening on the year before.

The key thing HAM measures is how many current renters would find it difficult to make mortgage payments on a starter home in their area, using a benchmark of residual income left over after housing costs.

That benchmark is derived from what the average household across the country has left after housing costs - currently $684 a week for a single person. If a renter would have below that amount left over after mortgage payments on a starter home in their area, the measure reads their housing costs as unaffordable.

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The figures show worsening affordability for homebuyers in Auckland, Wellington, Canterbury, and across the country, on a similar trend line to earlier years.

Using that benchmark 79.86 per cent of all renting households could not comfortably afford a first home, with 84.23 per cent of Aucklands unable to afford one. The Auckland figures are up almost two points on the same time in 2016.

Another benchmark looked at whether renting households would be highly stressed if paying mortgage costs - with just $222 left over a week after paying mortgage costs for a single person, or $337 for a couple.

Almost two thirds (63.4 per cent) of Auckland renters fell even below that benchmark, up from under half in 2012.

But renting affordability, also measured by HAM, had mostly evened out.

Around 60 per cent of renters fell below the main benchmark nationally just after paying their rent - not hypothetical mortgage payments - but this was mostly unchanged since the year before.

The trend of worsening affordability appears to have begun in 2012.

Housing Minister Phil Twyford said the measure showed without a doubt there was a housing crisis.

"I don't think anyone is under any illusion that this isn't a crisis. Even the opposition now use the word 'housing crisis,'" Twyford said.

"[HAM] shows sadly that things are continuing to get worse in all five major centres housing is less affordable."

"Things are likely to get worse before they get better."

He said fixing it with "massive interventions" like KiwiBuild would take years but he was not "fatalistic."

National's housing spokeswoman Judith Collins said you could call it whatever you liked but it was clear there were more people than there were houses to house them.

"We've got more people than we've got houses for. And also people's wages aren't keeping up with the costs of borrowing," Collins said.

She thought the issue was going to get worse before it got better, and said substantial reform of planning laws was needed to fix the issue.

Collins noted that National tried to substantially reform planning laws in Government but had found no support from Labour, the Green Party, NZ First, or governing partner United Future.

HAM was introduced as an experimental measure last year after almost two years of delays.

The measure uses individual-level data on the income of renters in each area alongside what a lower quartile house would cost, leading to a much richer picture than other measures.

Officials at the Ministry of Business Innovation and Employment (MBIE) who built the tool wrote that they were worried about a "lack of ministerial agreement" with the measure in a 2016 briefing released to Stuff under the Official Information Act.

Across the country, the measure shows a gradual increase in housing unaffordability disrupted by the financial crisis in 2008, then stabilising since. In Auckland, a marked increase in unaffordability is shown after 2013, while Canterbury has become steadily more affordable.

Spokespeople have been at pains to note that the measure was "relative" and looked at changes in affordability over time, rather than an absolute measure of what the Government considers unaffordable, which they say is too subjective to nail down.