According to census data, Croatia's population continuously grew in the period from 1971 to 1991, after which, starting in 2001, it recorded a decline.

In the 2021 Census, the smallest population in recent history was recorded, a total of 3,871,833, and at the same time the smallest number of families was also recorded, 1,104,395, which clearly shows long-term demographic changes. In the same period, the average household size also decreased; while in 1971 an average of 3.4 people lived in one household, in 2021 that number fell to 2.7, reflecting changes in family structures and lifestyle.

The data also clearly show strong population ageing. According to the 1971 Census, the average age of the population was 34 years, while according to the 2021 Census the average rose to 44.3 years, placing Croatia among the oldest countries in Europe. Differences between men and women are also evident: men are younger on average (42.6 years), and women older (46 years). It is important to note that census data from 2011 and 2021 are not completely methodologically comparable with earlier censuses, but the trends are clear and continuous.

Mid-2024 estimates show a slight increase in population to 3,866,233, representing an increase of 6,547 people or 0.2% compared with the previous year. This slight increase is not strong enough to change long-term demographic trends, but it signals possibly somewhat more stable migration and occasional natural population inflows.

Population ageing has multiple social and economic consequences, including increased needs for healthcare and social care, a reduction in the working-age population, and greater pressure on the pension system. In the long term, such trends affect the planning of public policies, education, and infrastructure development, because an increasingly older population requires a different type of services and support.

Changes in family structures are also significant. The decrease in the average number of household members and the growth in the number of single-person households reflect social changes, including later entry into marriage, a lower birth rate, and increased mobility of young people. These changes have a direct impact on the real estate market, consumer habits, and urban planning.

According to available data from the Croatian Bureau of Statistics and the population census, Croatia is facing one of the most pronounced ageing trends in Europe, which requires careful strategic planning and adaptation of social and economic policies in order to preserve the quality of life of all generations.