Two small objects offer a striking glimpse of demographic change in Japan and South Korea: a nappy and a pram. But the numbers behind them answer different questions.In Japan, more than 10 billion adult incontinence products were produced in 2025, against just over 7.1 billion baby nappies. That is a comparison by number of pieces. The adult count includes pads and liners as well as nappies and pants. It measures production, which is not necessarily the same as the number bought or used in Japan.
When adult nappies overtook baby nappies
South Korea’s 2025 finding looks similar at first: 61,418 tonnes of adult products supplied, compared with 54,001 tonnes of child products. The adult category overtook the child category by weight in 2024 and stayed ahead in 2025. But a heavier pile need not contain more nappies. Both Korean categories also include hygiene underpads.How different might the count be? One Japanese study calculated an average weight of 62.4g for an adult nappy and 32.1g for a baby nappy. Applying those weights to Korea’s supply gives the following illustration, not an estimate of actual Korean sales:
Those weights come from Japan and do not account for the mix of products in Korea’s supply. They cannot establish Korea’s actual piece count. They do show why the distinction matters: adult supply weighs about 14% more, yet could comprise fewer individual products. For adult products to lead by number, their average weight would have to be less than about 14% greater than the child average.The pram finding has a different boundary. On Gmarket, a South Korean online shopping marketplace, pet strollers accounted for 58% of pet and baby stroller sales by number through September 2024; baby strollers accounted for 42%. The result describes sales on Gmarket. It does not tell us which type sold more across every shop in South Korea, or how many homes have pets and children.
Pet strollers sell more than baby strollers
The three figures are revealing when read precisely: Japan’s adult products lead by pieces produced; Korea’s adult products lead by weight supplied; and pet strollers led on Gmarket. Each captures part of a changing market. The unit and the source determine exactly what we can say about it.
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