If your products don't seem to be going the distance they used to, it could be because they have shrunk in size.

Statistics New Zealand said a number of consumer items, ranging from orange juice to toilet paper, have become smaller while prices remained the same.

The government agency collects data on size and volume changes for "quality adjustment" in the Consumers Price Index to ensure smaller product size for the same price is measured as inflation for consumers.

The products which shrank the most included ice cream, which lost 400g going from 2lt to 1.6lt, and orange juice, which went from 3lt to 2.5lt, shedding 500mls.

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Butter dropped some weight, going from 500g to 400g. Shampoo lost 50ml, going from 400ml to 350ml.

Other, harder to measure, drops included canned pineapples and paper towels, which did not drop in sheets, but in width and length. Toilet paper, on the other hand, lost some sheets.

Statistics NZ told the Herald changes in size normally require a change in barcode, which makes it easy for the government agency to track.

It's not all bad news however, changes in the market can also result in a better deal. After a drop in the price of sugar, packs of lollies increased in size from around 190-200g to 220g.

Likewise, breakfast biscuits (for instance, Weet-Bix) increased from 1kg to 1.2kg.
Kiwis also see benefits in consumer technology where prices remain consistent while features improve.

Senior manager for prices at Stats NZ, Jason Attewell, said there were no macroeconomic forces at play when it came to size adjustments. Rather, it was commodity specific and came down to industry movements such as the change in dairy prices.

Other changes are a matter of consistency or improvement.

Laundry powder dropped in size by 50 per cent when manufacturers began putting in double concentrate, for instance, while beer cans dropped in size to fall in line with the volume of bottles.