South Korea's population is anticipated to decrease 1 per cent annually starting 2054 due to rapid aging and chronically low birthrates, government data showed on Thursday.

The population is forecast to drop by 1.03 per cent in 2054 compared to a year earlier, with the on-year population reduction ratio set to be more than 1 per cent afterward, according to data from Statistics Korea.

If there is no significant change to rapid aging and declining birthrates, the population is expected to shrink to below 20 million in 100 years from last year's 51 million, it said as quoted by Yonhap news agency report.

South Korea is experiencing grim demographic changes, as many young people opt to postpone or give up on getting married or having babies in line with changing social norms and lifestyles amid high home prices, a tough job market and an economic slowdown.

Last year, the number of babies born in the country dropped 7.7 per cent on-year to an all-time low of 229,970.

The total fertility rate, which means the average number of expected births from a woman in her lifetime, also hit a record yearly low of 0.72, which came far below the 2.1 births per woman needed to maintain a stable population without immigration.

In the fourth quarter of last year alone, the rate came to 0.65, the lowest-ever quarterly figure.

South Korea is expected to be a highly aged country by 2072 as the median age will increase from 44.9 in 2022 to 63.4 in 2072.