For two people over 65 living in a city the cost of a "no-frills" lifestyle was $872.22.

The gap between NZ Super and the cost of living even a "no frills" lifestyle has widened, research from Massey University shows.

Fortunately, many retiring Kiwis seem to be bridging the gap from their own savings, while others keep afloat by continuing to work beyond the age of 65.

The Westpac-Massey Fin-Ed Centre's annual Retirement Expenditure Guidelines show that for a two-person household of over 65 year-olds the cost of a "no-frills" lifestyle in a city was $872.22 a week at the end of June last year.

That was $271.92 more than NZ Super paid to a couple.

123RF NZ Super may be liveable, if you own your own home, but savings are needed to turn liveable into choices.

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Life was easier for a couple on the provinces, who had a shortfall of $21.18 a week to make up.

People managing on their own generally had a harder go of it in retirement than couples.

Single people faced making up a gap of $200.24 a week for a no frills lifestyle in cities, or a shortfall of $170.84 in the provinces.

No frills is the term the Fin-Ed Centre uses for a basic lifestyle with minimal spending on luxuries like entertainment and travel.

But the gap that needs to be bridged to achieve it does not equate to NZ Super being impossible to live on.

The Fin-Ed Centre's "no frills" lifestyle weekly costs are based on actual spending of households of one and two people receiving NZ Super.

The no frills expenditure is the average amount spent by the households in the second to bottom fifth of households ranked by their spending.

That means a fifth of one and two-person households receiving NZ Super are getting by on less.

The data also does not catch many NZ Super recipients living in multi-generational households, sharing life's costs with their adult children.

A "choices" lifestyle, which equated to the average spending level of the second to top fifth of one and two-person households receiving NZ Super, is what most people hope for in retirement.

To achieve this lifestyle, NZ Super recipients need to have saved sizeable nest eggs, or continue working, to bridge the gap with NZ Super.

For a couple, both getting NZ Super, the weekly shortfall that needed bridging to get a choices lifestyle in a city was $799.42, and $504.48 in the provinces.

For a single retiree, the shortfalls were $784.97 for a city choices lifestyle and $433.96 in the provinces.

The university estimated those nest eggs needed to range from $167,000 (a no frills, provincial lifestyle) to $769,000 (a choices, city lifestyle) for single people, and $21,000 to $783,000​ for couples.

Large as the gaps appear, Massey University's Claire Matthews said they indicated something quite positive, which was that many NZ Super recipients actually had the wealth and work to avoid living on NZ Super alone.

In fact, the cost of living a "no frills" existence for one and two-person households had risen as a result of the expenditure of those households rising faster than inflation, probably because they possessed the wealth to spend more than previous cohorts of retirees, perhaps as a result of people cashing up equity in homes.

"To some extent, this reflects households being better prepared for retirement, allowing them to top up their superannuation payments to give them the lifestyle they want," Matthews said.

SUPPLIED Claire Matthews from Massey University's Fin-Ed Centre said half of NZ Super recipients who enjoy a "choices" lifestyle after age 65 do so by continuing to work.

The guidelines report showed the importance of continuing to work after the age of 65 on people's financial wellbeing.

The data showed around half of retirees living a "choices" lifestyle were still working, at least part-time.

"It seems that reaching eligibility for NZ Super doesn't mean stopping working for many," Matthews said.

"While it can mean a change in working patterns and styles, semi-retirement offers people options for topping up their superannuation and saving more for when they do stop working completely."