One dollar each or three for five? Quantity surcharges in New Zealand supermarkets

A quantity surcharge occurs when a larger package costs more per unit than a smaller one. Although counterintuitive, such surcharges are common in supermarket pricing. Using manually collected price data from 1,491 product-type–store observations across 38 New Zealand supermarkets, we document their prevalence and distribution. Quantity surcharges affect roughly one in four products, a rate comparable to international evidence. Contrary to our initial expectation, they appear less prevalent in rich neighbourhoods. They also vary sharply across product categories.