Japan's average household is projected to have fewer than two members by 2033.
The National Institute of Population and Social Security Research on Friday released estimates showing the average household would have 1.99 members in 2033 and 1.92 in 2050, compared with 2.21 in 2020.
The ratio of single-person households will rise to 44.3 percent in 2050 from 38 percent in 2020.
The ratio of solo households among those aged 65 or older is projected to increase to 26.1 percent for men and 29.3 percent for women in 2050.
The institute attributes the trend to the increasing number of people who remain unmarried.
The institute estimates that among elderly men who live by themselves, almost 60 percent will be unmarried in 2050. The percentage for women will be 30 percent.
Fujii Takiko, who worked on the projection, says the percentage of unmarried people is high among those who are around 50 years old.
She calls for measures to help single elderly people manage their finances and get nursing care.